Search results for: atomic layer deposition (ALD)

Authors: Haluk Özparlak, Murad Aydın Şanda, Gülşin Arslan

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Phoxinellus anatolicus, Carassius gibelio, Sander lucioperca, Vimba vimba tenella, Capoeta capoeta, Tinca tinca from Suğla Lake (Turkey) and Phoxinellus anatolicus, Scardinius erythrophthalmus, Tinca tinca from Beyşehir Lake (Turkey) are economically important fish species and these fish have been consumed as food by local people. P. anatolicus is also endangered and endemic species from Turkey. In this study, concentrations of Cd, Co, Cr, Fe, Mn, Ni, Pb and Zn were determined in muscle tissue of these fish by using atomic absorption spectrophotometer. Levels of metals in the muscle tissue of all the fish specimens were compared with results of previous studies, the tolerance levels of national and international guidelines and the levels of Provisional Tolerable Weekly Intake (PTWI) limits set by FAO/WHO. Concentrations of Cd, Cr, Ni and Pb in the muscle tissue of all the fish specimens from Suğla and Beyşehir Lakes exceeded the tolerance levels of national and international guidelines. However, concentrations of Cd, Fe, Pb and Zn were below PTWI limits. Therefore, in terms of these metal levels, consumption of fresh filet of examined seven fish species (weekly up to about 300 g/person) doesn’t seem to be objectionable for human health.

Keywords: Beyşehir Lake, fish, metal levels, Suğla Lake

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Authors: Abdelhadi Lotfi, Abdelkader Benyettou

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In this work, a training algorithm for probabilistic neural networks (PNN) is presented. The algorithm addresses one of the major drawbacks of PNN, which is the size of the hidden layer in the network. By using a cross-validation training algorithm, the number of hidden neurons is shrunk to a smaller number consisting of the most representative samples of the training set. This is done without affecting the overall architecture of the network. Performance of the network is compared against performance of standard PNN for different databases from the UCI database repository. Results show an important gain in network size and performance.

Keywords: classification, probabilistic neural networks, network optimization, pattern recognition

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Authors: Vikas Kumar

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Portable batteries are reliable source of mobile energy to power smart wearable electronics, medical devices, communications, and others internet of thing (IoT) devices. There is a continuous increase in demand for thinner, more flexible battery with high energy density and reliability to meet the requirement. For a flexible battery, factors that affect these properties are the stability of current collectors, electrode materials and their interfaces with the corrosive electrolytes. State-of-the-art conventional and flexible batteries utilise carbon as an electrode and current collectors which cause high internal resistance (~100 ohms) and limit the peak current to ~1mA. This makes them unsuitable for a wide range of applications. Replacing the carbon parts with metallic components would reduce the internal resistance (and hence reduce parasitic loss), but significantly increases the risk of corrosion due to galvanic interactions within the battery. To overcome these challenges, low cost electroplated nickel (Ni) on copper (Cu) was studied as a potential anode current collector for a zinc-manganese oxide primary battery with different concentration of NH4Cl/ZnCl2 electrolyte. Using electrical impedance spectroscopy (EIS), we monitored the open circuit potential (OCP) of electroplated nickel (different thicknesses) in different concentration of electrolytes to optimise the thickness of Ni coating. Our results show that electroless Ni coating suffer excessive corrosion in these electrolytes. Corrosion rates of Ni coatings for different concentrations of electrolytes have been calculated with Tafel analysis. These results suggest that for electroplated Ni, channelling and/or open porosity is a major issue, which was confirmed by morphological analysis. These channels are an easy pathway for electrolyte to penetrate thorough Ni to corrode the Ni/Cu interface completely. We further investigated the incorporation of a special printed graphene layer on Ni to provide corrosion protection in this corrosive electrolyte medium. We find that the incorporation of printed graphene layer provides the corrosion protection to the Ni and enhances the chemical bonding between the active materials and current collector and also decreases the overall internal resistance of the battery system.

Keywords: corrosion, electrical impedance spectroscopy, flexible battery, graphene, metal current collector

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Authors: Pheiroijam Pooja, P. Chinnamuthu

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A novel vertical 1D In2O3/TiO2 nanocolumn (NC) axial heterostructure has been successfully synthesized using Glancing Angle Deposition (GLAD) technique inside E-Beam Evaporator chamber. Field emission scanning electron microscope (FESEM) has been used to evaluate the morphology of the structure grown. The estimated length of In2O3/TiO2 NC is ~250 nm and ~300nm for In2O3 and TiO2 respectively with diameter ~60-90 nm. The surface of the heterostructure is porous in nature which can affect the interfacial wettability properties. The grown structure has been further characterized using X-ray Diffraction (XRD) and UV-Visible absorption measurement. The polycrystalline nature of the sample has been examined using XRD with prominent peaks obtained with phase (101) for anatase TiO2 and (211) for In2O3. Here, 1D axial heterostructure NC thus favors efficient segregation of photo-excited carriers due to their type II band alignment between the constituent materials. Moreover, the 1D nanostructure is known for their large surface area and excellent ionic charge transport property. On exposure to UV light illumination, the surface properties of In2O3/TiO2 NC changes whereby the hydrophobic nature of the heterostructure changes to hydrophilic. As a result, the reversible surface wettability of heterostructure on interaction with UV light can give potential applications as antifogging and self-cleaning surfaces.

Keywords: GLAD, heterostructure, In2O3/TiO2 NC, surface wettability

Procedia PDF Downloads 164

Authors: Jun Wang, Chenglei Diao, Emanuele Pagone, Jialuo Ding, Stewart Williams

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As a crucial component in aircraft, landing gear systems are responsible for supporting the plane during parking, taxiing, takeoff, and landing. Given the need for high load-bearing capacity over extended periods, 300M ultra-high strength steel (UHSS) is often the material of choice for crafting these systems due to its exceptional strength, toughness, and fatigue resistance. In the quest for cost-effective and sustainable manufacturing solutions, Wire Arc Additive Manufacturing (WAAM) emerges as a promising alternative for fabricating 300M UHSS landing gears. This is due to its advantages in near-net-shape forming of large components, cost-efficiency, and reduced lead times. Cranfield University has conducted an extensive preliminary study on WAAM 300M UHSS, covering feature deposition, interface analysis, and post-heat treatment. Both Gas Metal Arc (GMA) and Plasma Transferred Arc (PTA)-based WAAM methods were explored, revealing their feasibility for defect-free manufacturing. However, as-deposited 300M features showed lower strength but higher ductility compared to their forged counterparts. Subsequent post-heat treatments were effective in normalising the microstructure and mechanical properties, meeting qualification standards. A 300M UHSS landing gear demonstrator was successfully created using PTA-based WAAM, showcasing the method's precision and cost-effectiveness. The demonstrator, measuring Ф200mm x 700mm, was completed in 16 hours, using 7 kg of material at a deposition rate of 1.3kg/hr. This resulted in a significant reduction in the Buy-to-Fly (BTF) ratio compared to traditional manufacturing methods, further validating WAAM's potential for this application. A "cradle-to-gate" environmental impact assessment, which considers the cumulative effects from raw material extraction to customer shipment, has revealed promising outcomes. Utilising Wire Arc Additive Manufacturing (WAAM) for landing gear components significantly reduces the need for raw material extraction and refinement compared to traditional subtractive methods. This, in turn, lessens the burden on subsequent manufacturing processes, including heat treatment, machining, and transportation. Our estimates indicate that the carbon footprint of the component could be halved when switching from traditional machining to WAAM. Similar reductions are observed in embodied energy consumption and other environmental impact indicators, such as emissions to air, water, and land. Additionally, WAAM offers the unique advantage of part repair by redepositing only the necessary material, a capability not available through conventional methods. Our research shows that WAAM-based repairs can drastically reduce environmental impact, even when accounting for additional transportation for repairs. Consequently, WAAM emerges as a pivotal technology for reducing environmental impact in manufacturing, aiding the industry in its crucial and ambitious journey towards Net Zero. This study paves the way for transformative benefits across the aerospace industry, as we integrate manufacturing into a hybrid solution that offers substantial savings and access to more sustainable technologies for critical component production.

Keywords: WAAM, aircraft landing gear, microstructure, mechanical performance, life cycle assessment

Procedia PDF Downloads 159

Authors: Muhammad Younus, Muhammad Sajid, Muti-ur-Rehman Khan, Aftab Ahmad Anjum, Muhammad Asif Idrees, Iahtasham Khan, Aman Ullah Khan, Sajid Umar, Raheela Akhtar

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The present study was conducted to investigate the hazardous effects of lead on health and edible organs of Lohi sheep. The adult Lohi sheep (n=48) were randomly divided into two equal groups. The first group was administered lead acetate at dose of 70 mg/kg live body weight daily as 10% solution by oral route for a period of 90 days and the second group served as a negative control. Blood and tissue samples were collected at day 0, 30, 60 and 90 and analyzed for lead concentration by atomic absorption spectrophotometry. The kidney showed the highest lead concentration (p < 0.05) followed by liver and then muscle. Lead acetate treated sheep showed structural and behavioral changes during the last month of trial. Liver showed necrosis, hemorrhages and hyperactivation of macrophages. Kidney showed degenerative and necrotic changes in glomeruli and tubules and the characteristic intranuclear inclusion bodies in tubular epithelial cells on H and E staining. It was concluded that Lohi sheep is affected by lead intoxication at low dose for longer period and hence exhibits lead accumulation in edible tissues.

Keywords: Lohi sheep, lead acetate, edible tissue, histopathology

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Authors: Keshav Prasad Kandel, Balaram Khadka, Karan Bhatta, Basu Dev Ghimire

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Earthquakes still exist as a threating disaster. Being able to predict earthquakes will certainly help prevent substantial loss of life and property. Perhaps, Very Low Frequency/Low Frequency (VLF/LF) signal band (3-30 kHz), which is effectively reflected from D-layer of ionosphere, can be established as a tool to predict earthquake. On May 20 and May 29, 2012, earthquakes of magnitude 6.1 and 5.8 respectively struck Emilia-Romagna of Italy. A year back, on August 24, 2016, an earthquake of magnitude 6.2 struck Central Italy (42.7060 N and 13.2230 E) at 1:36 UT. We present the results obtained from the US Navy VLF Transmitter’s NSY signal of 45.9 kHz transmitted from Niscemi, in the province of Sicily, Italy and received at the Kiel Longwave Monitor, Germany for 2012 and 2016. We analyzed the terminator times, their individual differences and nighttime fluctuation counts. We also analyzed trends, dispersion and nighttime fluctuation which gave us a possible precursors to these earthquakes. Since perturbations in VLF amplitude could also be due to various other factors like lightning, geomagnetic activities (storms, auroras etc.) and solar activities (flares, UV flux, etc.), we filtered the possible perturbations due to these agents to guarantee that the perturbations seen in VLF/LF amplitudes were as a precursor to Earthquakes. As our TRGCP path is North-south, the sunrise and sunset time in transmitter and receiver places matches making pathway for VLF/LF smoother and therefore hoping to obtain more natural data. To our surprise, we found many clear anomalies (as precursors) in terminator times 5 days to 16 days before the earthquakes. Moreover, using night time fluctuation method, we found clear anomalies 5 days to 13 days prior to main earthquakes. This exactly correlates with the findings of previous authors that ionospheric perturbations are seen few days to one month before the seismic activity. In addition to this, we were amazed to observe unexpected decrease of dispersion on certain anomalies where it was supposed to increase, thereby not supporting our finding to some extent. To resolve this problem, we devised a new parameter called dispersion nighttime (dispersion). On analyzing, this parameter decreases significantly on days of nighttime anomalies thereby supporting our precursors to much extent.

Keywords: D-layer, TRGCP (Transmitter Receiver Great Circle Path), terminator times, VLF/LF

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Authors: H. Vahdani

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By the adsorption of polar compounds and/or the deposition of organic material, the wettability of originally water-wet reservoir rock can be altered. The degree of alteration is determined by the interaction of the oil constituents, the mineral surface, and the brine chemistry. Recently improving oil recovery by tuning wettability alteration is believed as a new recovery method. Various researchers have demonstrated that low salt water injection has a significant impact on oil recovery. It has been shown, for instance, that additional oil can be produced from reservoir rock by managing the injection water. Large wettability sensitivity has been observed, indicating that the oil/water capillary pressure profiles play a major role during low saline water injection simulation. Although the exact physics on how this alteration occurs is still a research topic; however, it has been reported that some of its effect can be captured by a relative permeability shift from an oil-wet system to a water-wet system. Modeling of low salt water injection mainly is based on the theory of wettability alteration and is hence strongly dependent on the wettability of the reservoir. In this article, combination of different wettabilities has been simulated and it is observed that the highest recoveries were from the cases were the reservoir initially was water-wet, and the lowest recoveries was from the cases were the reservoir initially was considered oil-wet. However for the cases where the reservoir initially was oil-wet, the effect of low-salinity waterflooding was the largest.

Keywords: low salt water injection, wettability alteration, modelling, relative permeability

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Authors: Okorowo Cyril Agochi

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The Niger Delta Region of Nigeria is home to about 20 million people and 40 different ethnic groups. The region has an area of seventy thousand square kilometers (70,000 KM2) of wetlands, formed primarily by sediments deposition and makes up 7.5 percent of Nigeria's total landmass. The notable ecological zones in this region includes: coastal barrier islands; mangrove swamp forests; fresh water swamps; and lowland rainforests. This incredibly naturally-endowed ecosystem region, which contains one of the highest concentrations of biodiversity on the planet, in addition to supporting abundant flora and fauna, is threatened by the inhuman act known as gas flaring. Gas flaring is the combustion of natural gas that is associated with crude oil when it is pumped up from the ground. In petroleum-producing areas such as the Niger Delta region of Nigeria where insufficient investment was made in infrastructure to utilize natural gas, flaring is employed to dispose of this associated gas. This practice has impoverished the communities where it is practiced, with attendant environmental, economic and health challenges. This paper discusses the adverse environmental and health implication associated with the practice, the role of Government, Policy makers, Oil companies and the Local communities aimed at bring this inhuman practice to a prompt end.

Keywords: natural combustion, emission, environment, flaring, gas, health, Niger Delta

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Authors: David E. Esezobor, Friday I. Apeh, Harrison O. Onovo, Ademola A. Agbeleye

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Available indigenous refractory bricks in Nigeria can only be used in the lining of furnaces for melting of cast iron operating at less than 1,400°C or in preheating furnaces due to their low refractoriness less than 1,500°C. The bricks crack and shatter on heating at 1350 to 1450°C. In this paper, a simple and adaptable technology of manufacturing high-quality refractory bricks from selected Nigerian clays for furnace linings was developed. Fireclays from Onibode, Owode-Ketu in Ogun State and Kwoi in Kaduna State were crushed, ground, and sieved into various grain sizes using standard techniques. The pulverized clays were blended with alumina in various mix ratios and indurated in the furnace at 900 – 16000C. Their chemical, microstructure and mineralogical properties were characterized using atomic absorption spectrophotometry, scanning electron microscopy and x-ray diffraction spectrometry respectively. The mineralogical and spectrochemical analyses suggested that the clays are of siliceous alumino-silicate and acidic in nature. The appropriate blending of fireclays with alumina provided the tremendous improvement in the refractoriness of the bricks and other acceptable service properties comparable with imported refractory bricks. The change in microstructure from pseudo-hexagonal grains to equiaxed grains of well – ordered sequence of structural layers could be responsible for the improved properties.

Keywords: alumina, furnace, industry, manufacturing, refractoriness

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Authors: Muhammad Jawad Hashmi

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The idea of nuclear terrorism is as old as nuclear weapons but the global concerns of likelihood of nuclear terrorism are uncertain. Post 9/11 trends manifest that terrorists are believers of massive causalities. Innovation in terrorist’s tactics, sophisticated weaponry, vulnerability, theft and smuggling of nuclear/radiological material, connections between terrorists, black market and rough regimes are signaling seriousness of upcoming challenges as well as global trends of “terror-transnationalism.” Furthermore, the International-Atomic-Energy-Agency’s database recorded 2734 incidents regarding misuse, unauthorized possession, trafficking of nuclear material etc. Since, this data also includes incidents from south Asia, so, there is every possibility to claim that such illicit activities may increase in future, mainly due to expansion of nuclear industry in South Asia. Moreover, due to such mishaps the region is vulnerable to threats of nuclear terrorism. This is also a reason that the region is in limelight along with issues such as rapidly growing nuclear arsenals, nuclear safety and security, terrorism and political instability. With this backdrop, this study is aimed to investigate the prevailing threats and challenges in South Asia vis a vis nuclear safety and security. A comparative analysis of the overall capabilities would be done to identify the areas of cooperation to eliminate the probability of nuclear/radiological terrorism in the region.

Keywords: nuclear terrorism, safety, security, South Asia, india, Pakistan

Procedia PDF Downloads 356

Authors: R. F. B. Gonçalves, E. N. Iwama, J. A. F. F. Rocco, K. Iha

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Propellants based on Hydroxyl Terminated Polybutadiene/Ammonium Perchlorate (HTPB/AP) are the most commonly used in most of the rocket engines used by the Brazilian Armed Forces. This work aimed at the possibility of extending its useful life (currently in 10 years) by performing kinetic-chemical analyzes of its energetic material via Differential Scanning Calorimetry (DSC) and also performing computer simulation of aging process using the software Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS). Thermal analysis via DSC was performed in triplicates and in three heating ratios (5 ºC, 10 ºC, and 15 ºC) of rocket motor with 11 years shelf-life, using the Arrhenius equation to obtain its activation energy, using Ozawa and Kissinger kinetic methods, allowing comparison with manufacturing period data (standard motor). In addition, the kinetic parameters of internal pressure of the combustion chamber in 08 rocket engines with 11 years of shelf-life were also acquired, for comparison purposes with the engine start-up data.

Keywords: shelf-life, thermal analysis, Ozawa method, Kissinger method, LAMMPS software, thrust

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Authors: Nicholas Sehube, Rosemary Kelebemang, Pogisego Dinake

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The extent of Pb contamination of shooting range soils has never been ascertained in Botswana, this was the first attempt in evaluating the deposition of Pb into the soils emanating from munitions. A total of 8 military shooting ranges were used for this study. Soil samples were collected at each of the 8 shooting ranges at the berm (stop butt), target line, 50 and 100 m from the berm. In all of the shooting ranges investigated the highest concentrations were found in the berm soils. The highest Pb concentrations of 38 406.87 mg/Kg were found in the berm soils of Thebephatshwa shooting range which is enclosed within a military camp with staff residential dwelling only a kilometre away. Most of the shooting ranges soils contained elevated levels of Pb in the ranges above 2000 mg/kg far exceeding the United States Environmental Protection Agency (USEPA) critical value of 400 mg/Kg. Mobilization of lead at high pH is attributed to low organic matter and such was the case with Thebephatshwa shooting range with a percept organic matter of 0.35±0.08. The predominant weathering products in these shooting ranges were cerussite (PbCO3), hydrocerussite (Pb(CO3)2(OH)2 and massicot (PbO). The detailed examination and characterization of the extent of pollution will help in the development and implementation of scientifically sound remediation and restoration of shooting ranges soils.

Keywords: ammunition, Botswana, Pb, pollution, soil

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Authors: Juan Xia, Jiaxu Yan, Ze Xiang Shen

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The tuneable interlayer interactions in two-dimensional (2D) transition metal dichlcogenides (TMDs) offer an exciting platform for exploring new physics and applications by material variety, thickness, stacking sequence, electromagnetic filed, and stress/strain. Compared with the five methods mentioned above, high pressure is a clean and powerful tool to induce dramatic changes in lattice parameters and physical properties for 2D TMD materials. For instance, high pressure can strengthen the van der Waals interactions along c-axis and shorten the covalent bonds in atomic plane, leading to the typical first-order structural transition (2Hc to 2Ha for MoS2), or metallization. In particular, in the case of WTe₂, its unique symmetry endows the significant anisotropy and the corresponding unexpected properties including the giant magnetoresistance, pressure-induced superconductivity and Weyl semimetal states. Upon increasing pressure, the Raman peaks for WTe₂ at ~120 cm⁻¹, are gradually red-shifted and totally suppressed above 10 GPa, attributed to the possible structural instability of orthorhombic Td phase under high pressure and phase transition to a new monoclinic T' phase with inversion symmetry. Distinct electronic structures near Fermi level between the Td and T' phases may pave a feasible way to achieve the Weyl state tuning in one material without doping.

Keywords: 2D TMDs, electronic property, high pressure, first-principles calculations

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Authors: N. H. Z. Abidin, N. F. M. Mokhtar, S. S. A. Gani

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The influence of diffusion of the thermal or known as Soret effect in a heated Binary fluid model with Coriolis force is investigated theoretically. The linear stability analysis is used, and the eigenvalue is obtained using the Galerkin method. The impact of the Soret and Coriolis force on the onset of stationary convection in a system is analysed with respect to various Binary fluid parameters and presented graphically. It is found that an increase of the Soret values, destabilize the Binary fluid layer system. However, elevating the values of the Coriolis force helps to lag the onset of convection in a system.

Keywords: Benard convection, binary fluid, Coriolis, Soret

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Authors: Radhe Tado, Ashish B. Deoghare, K. M. Pandey

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The aim of this study is to estimate the effect of blood flow through the coronary artery in human heart so as to assess the coronary artery disease.Velocity, wall shear stress (WSS), strain rate and wall pressure distribution are some of the important hemodynamic parameters that are non-invasively assessed with computational fluid dynamics (CFD). These parameters are used to identify the mechanical factors responsible for the plaque progression and/or rupture in left coronary arteries (LCA) in coronary arteries.The initial step for CFD simulations was the construction of a geometrical model of the LCA. Patient specific artery model is constructed using computed tomography (CT) scan data with the help of MIMICS Research 19.0. For CFD analysis ANSYS FLUENT-14.5 is used.Hemodynamic parameters were quantified and flow patterns were visualized both in the absence and presence of coronary plaques. The wall pressure continuously decreased towards distal segments and showed pressure drops in stenotic segments. Areas of high WSS and high flow velocities were found adjacent to plaques deposition.

Keywords: angiography, computational fluid dynamics (CFD), time-average wall shear stress (TAWSS), wall pressure, wall shear stress (WSS)

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Authors: Shahab Azimi, Siamak Arzanpour, Anahita Sayyar

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Asthma and Chronic obstructive pulmonary disease (COPD) are common lung diseases that have a significant global impact. Pressurized metered dose inhalers (pMDIs) are widely used for treatment, but they can have limitations such as high medication release speed resulting in drug deposition in the mouth or oral cavity and difficulty achieving proper synchronization with inhalation by users. Spacers are add-on devices that improve the efficiency of pMDIs by reducing the release speed and providing space for aerosol particle breakup to have finer and medically effective medication. The aim of this study is to optimize the size and cylindrical shape of spacers to enhance their drug delivery performance. The study was based on fluid dynamics theory and employed Ansys software for simulation and optimization. Results showed that optimization of the spacer's geometry greatly influenced its performance and improved drug delivery. This study provides a foundation for future research on enhancing the efficiency of inhalation therapy for lung diseases.

Keywords: asthma, COPD, pressurized metered dose inhalers, spacers, CFD, shape optimization

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Authors: Esubalew Yehualaw Melaku, Tizazu Abeza

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ZnSe thin films in an aqueous solution of zinc acetate and hydrazine hydrate (HH) using the non-toxic complexing agent EDTA along with the films were annealed at 200, 300, and 400oC. This research aimed to investigate the effect of annealing on the structural, optical, and electrical properties of the films. X-ray diffraction (XRD) analysis was used to study the structure and crystallite size of the ZnSe thin film. The ZnSe thin films are annealed in an oven at various temperatures which are characterized by structural and optical properties. An increase in annealing temperature distorted the nanocrystillinity and made the ZnSe thin films amorphous. The variation of resistivity indicates the semiconducting nature of the thin film. The electrical resistivity of the films decreases with increasing annealing temperature. In this study, the Band gap of ZnSe decreases from 2.8eV to 2.65eV with the increase in temperature and decreases for as-deposited to 2.5eV. As a result of this research, ZnSe is used for certain applications; it has been widely utilized in various optoelectronic devices such as thin film solar cells, green-blue light emitting diodes, lasers, photo-luminescent, and electro-luminescent devices.

Keywords: chemical bath deposition, ZnSe thin film, band gap, solar cells

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Authors: Si Abdallah Mayouf

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In this work, the effects of the wavy surface on free convection heat transfer boundary layer flow between two parallel wavy plates have been studied numerically. The two plates are considered at a constant temperature. The equations and the boundary conditions are discretized by the finite difference scheme and solved numerically using the Gauss-Seidel algorithm. The important parameters in this problem are the amplitude of the wavy surfaces and the distance between the two wavy plates. Results are presented as velocity profiles, temperature profiles and local Nusselt number according to the important parameters.

Keywords: free convection, wavy surface, parallel plates, fluid dynamics

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Authors: Krestina V. Alsaraeva, Victor E. Gromov, Sergey V. Konovalov, Anna A. Atroshkina

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Processing of Al-19.4Si alloy by high intensive electron beam has been carried out and multiple increase in fatigue life of the material has been revealed. Investigations of structure and surface modified layer destruction of Al-19.4Si alloy subjected to multicycle fatigue tests to fracture have been carried out by methods of scanning electron microscopy. The factors responsible for the increase of fatigue life of Al-19.4Si alloy have been revealed and analyzed.

Keywords: Al-19.4Si alloy, high intensive electron beam, multicycle fatigue, structure

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Authors: Yogi Priyo Pradana, Heriansyah Putra, Regina Aprilia Zulfikar, Maulana Rafiq Ramadhan, Devyan Meisnnehr, Zalfa Maulida Insani

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This paper studied the effects and mechanisms of fine-grained tailing by Enzyme-Mediated Calcite Precipitation (EMCP). Grouting solution used consists of reagents (CaCl₂ and (CO(NH₂)₂) and urease enzymes which react to produce CaCO₃. In sample preparation, the test tube is used to investigate the precipitation rate of calcite. The grouting solution added is 75 mL for one mold sample. The solution was poured into a mold sample up to as high as 5 mm from the top surface of the tailing to ensure the entire surface is submerged. The sample is left open in a cylinder for up to 3 days for curing. The direct mixing method is conducted so that the cementation process occurs by evenly distributed. The relationship between the results of the UCS test and the calcite precipitation rate likely indicates that the amount of calcite deposited in treated tailing could control the strength of the tailing. The sample results are analyzed using atomic absorption spectroscopy (AAS) to evaluate metal and metalloid content. Calcium carbonate deposited in the tailing is expected to strengthen the bond between tailing granules, which are easily slipped on the banks of the tailing dam. The EMCP method is expected to strengthen tailing in erosion-control surfaces.

Keywords: tailing, EMCP, UCS, AAS

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Authors: Amine Harrane, Mahmoud Belalia

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During the last decade, polymer layered silicate nanocomposites have received increasing attention from scientists and industrial researchers because they generally exhibit greatly improved mechanical, thermal, barrier and flame-retardant properties at low clay content in comparison with unfilled polymers or more conventional micro composites. Poly(ε-caprolactone) (PCL)-layered silicate nanocomposites have the advantage of adding biocompatibility and biodegradability to the traditional properties of nanocomposites. They can be prepared by in situ ring-opening polymerization of ε-caprolactone using a conventional initiator to induce polymerization in the presence of an organophilic clay, such as organomodified montmorillonite. Messersmith and Giannelis used montmorillonite exchanged with protonated 12-amino dodecanoic acid and Cr3+ exchanged fluorohectorite, a synthetic mica type of silicate. Sn-based catalysts such as tin (II) octoate and dibutyltin (IV) dimethoxide have been reported to efficiently promote the polymerization of ε-caprolactone in the presence of organomodified clays. In this work, we have used an alternative method to prepare PCL/montmorillonite nanocomposites. The cationic polymerization of ε-caprolactone was initiated directly by Maghnite-TOA, organomodified montmorillonite clay, to produce nanocomposites (Scheme 1). Resulted from nanocomposites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), force atomic microscopy (AFM) and thermogravimetry.

Keywords: polycaprolactone, polycaprolactone/clay nanocomposites, biodegradables nanocomposites, Maghnite, Insitu polymeriation

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Authors: Kinjal Trivedi, Ramesh V. Upadhyay

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Magnetic fluid as a nanolubricant is a most recent field of study due to its unusual properties that can be tuned by applying a magnetic field. In present work, four ball tester has been used to investigate the tribological properties of the magnetic fluid having a 4 wt% of nanoparticles. The structural characterization of fluid shows crystallite size of particle is 11.7 nm and particles are nearly spherical in nature. The magnetic characterization shows the fluid saturation magnetization is 2.2 kA/m. The magnetic field applied using permanent strip magnet (0 to 1.6 mT) on the faces of the lock nut and fixing a solenoid (0 to 50 mT) around a shaft, such that shaft rotates freely. The magnetic flux line for both the systems analyzed using finite elemental analysis. The coefficient of friction increases with the application of magnetic field using permanent strip magnet compared to zero field value. While for the solenoid, it decreases at 20 mT. The wear scar diameter is lower for 1.1 mT and 20 mT when the magnetic field applied using permanent strip magnet and solenoid, respectively. The coefficient of friction and wear scar reduced by 29 % and 7 % at 20 mT using solenoid. The worn surface analysis carried out using Scanning Electron Microscope and Atomic Force Microscope to understand the wear mechanism. The results are explained on the basis of structure formation in a magnetic fluid upon application of magnetic field. It is concluded that the tribological properties of magnetic fluid depend on magnetic field and its applied direction.

Keywords: four ball tester, magnetic fluid, nanolubricant, tribology

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Authors: A. N. Fouda

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A novel well identified hexagonal graphene oxide (GO) nano-sheets were synthesized using modified Hummer method. Low temperature thermal reduction at 350°C in air ambient was performed. After thermal reduction, typical few layers of thermal reduced GO (TRGO) with dimension of few hundreds nanometers were observed using high resolution transmission electron microscopy (HRTEM). GO has a lot of structure models due to variation of the preparation process. Determining the atomic structure of GO is essential for a better understanding of its fundamental properties and for realization of the future technological applications. Structural characterization was identified by x-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FTIR) measurements. A comparison between exper- imental and theoretical IR spectrum were done to confirm the match between experimentally and theoretically proposed GO structure. Partial overlap of the experimental IR spectrum with the theoretical IR was confirmed. The electrochemical properties of TRGO nano-sheets as electrode materials for supercapacitors were investigated by cyclic voltammetry and electrochemical impedance spectroscopy (EIS) measurements. An enhancement in supercapacitance after reduction was confirmed and the area of the CV curve for the TRGO electrode is larger than those for the GO electrode indicating higher specific capacitance which is promising in super-capacitor applications

Keywords: hexagonal graphene oxide, thermal reduction, cyclic voltammetry

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Authors: Feng Xu, Zhaozhi Liu, Junhua Xu, Xiaolong Tang, Dunwen Zuo

Abstract:

Chemical vapor deposition (CVD) diamond coated cutting tool has excellent cutting performance, it is the most ideal tool for the processing of nonferrous metals and alloys, composites, nonmetallic materials and other difficult-to-machine materials efficiently and accurately. Depositing CVD diamond coating on the cemented carbide with high cobalt content can improve its toughness and strength, therefore, it is very important to research on the preparation technology and cutting properties of CVD diamond coated cemented carbide cutting tool with high cobalt content. The preparation technology of boron-doped diamond (BDD) coating has been studied and the coated drills were prepared. BDD coating were deposited on the drills by using the optimized parameters and the SEM results show that there are no cracks or collapses in the coating. Cutting tests with the prepared drills against the silumin and aluminum base printed circuit board (PCB) have been studied. The results show that the wear amount of the coated drill is small and the machined surface has a better precision. The coating does not come off during the test, which shows good adhesion and cutting performance of the drill.

Keywords: cemented carbide with high cobalt content, CVD boron-doped diamond, cutting test, drill

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Authors: Rahul Singha, D. Vakula

Abstract:

This paper presents a corrugated antipodal vivaldi antenna with improved performance by using negative index metamaterial (NIM) of the Archimedean spiral design. A single layer NIM piece is placed perpendicular middle of the two arm of the proposed antenna. The antenna size is 30×60×0.787 mm3 operating at 8GHz. The simulated results of NIM corrugated antipodal vivaldi antenna show that the gain and directivity has increased up to 1.2dB and 1dB respectively. The HPBW is increased by 90 with the reflection coefficient less than ‒10 dB from 4.7 GHz to 11 GHz for UWB application.

Keywords: Negative Index Metamaterial (NIM), Ultra Wide Band (UWB), Half Power Beam Width (HPBW), vivaldi antenna

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Authors: Nadia Bachir (Dahmani), Fatima Zohra Otmani

Abstract:

Due to its interesting optoelectronic properties, methylammonium perovskite CH3NH3PbI3 is used as the active layer in the development of several solar cells. In this work, the hybrid (organic-inorganic) cell with the architecture FTO/pedotpss/CH3NH3PbI3/pcdtbt/Al is simulated using the Organic and Hybrid Material Nano Simulation Tool (OghmaNano). We studied the influence of certain parameters, such as thickness, on the characteristics of the solar cell. The effect of the device temperature was also investigated. The photovoltaic characteristic curves, such as current-voltage (j-V), are presented in this work. The optimized final parameters are Voc = 0.947 V, FF = 0.8034%, and PCE = 23.16%.

Keywords: OghmaNano software, hybrid perovskite cell, CH3NH3PbI3, conversion efficiency

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Authors: Priyanka Yadav, Umesh Bnasal, Yashvinder Kumar

Abstract:

The placenta is an important structure that provides oxygen and nutrients to the growing fetus in utero. It is usually thrown away after birth, but it has a therapeutic role in the regeneration of tissue. It is covered by the amniotic membrane, which can be easily separated into the amnion layer and the chorion layer—the amnion layer act as a biofilm for the healing of burn wound and non-healing ulcers. The freshly collected membrane has stem cells, cytokines, growth factors, and anti-inflammatory properties, which act as a biofilm for the healing of wounds. It functions as a barrier and prevents heat and water loss and also protects from bacterial contamination, thus supporting the healing process. The application of Amnion membranes has been successfully used for wound and reconstructive purposes for decades. It is a very cheap and easy process and has shown superior results to allograft and xenograft. However, there are very few case reports of amnion membrane grafting in newborns; we intend to highlight its therapeutic importance in burn injuries in newborns. We present a case of 9 days old male neonate who presented to the neonatal unit of Maulana Azad Medical College with a complaint of fluid-filled blisters and burns wound on the body for six days. He was born outside the hospital at 38 weeks of gestation to a 24-year-old primigravida mother by vaginal delivery. The presentation was cephalic and the amniotic fluid was clear. His birth weight was 2800 gm and APGAR scores were 7 and 8 at 1 and 5 minutes, respectively. His anthropometry was appropriate for gestational age. He developed respiratory distress after birth requiring oxygen support by nasal prongs for three days. On the day of life three, he developed blisters on his body, starting from than face then over the back and perineal region. At a presentation on the day of life nine, he had blisters and necrotic wound on the right side of the face, back, right shoulder and genitalia, affecting 60% of body surface area with full-thickness loss of skin. He was started on intravenous antibiotics and fluid therapy. Pus culture grew Pseudomonas aeuroginosa, for which culture-specific antibiotics were started. Plastic surgery reference was taken and regular wound dressing was done with antiseptics. He had a storming course during the hospital stay. On the day of life 35 when the baby was hemodynamically stable, amnion membrane grafting was done on the wound site; for the grafting, fresh amnion membrane was removed under sterile conditions from the placenta obtained by caesarean section. It was then transported to the plastic surgery unit in half an hour in a sterile fluid where the graft was applied over the infant’s wound. The amnion membrane grafting was done twice in two weeks for covering the whole wound area. After successful uptake of amnion membrane, skin from the thigh region was autografted over the whole wound area by Meek technique in a single setting. The uptake of autograft was excellent and most of the areas were healed. In some areas, there was patchy regeneration of skin so dressing was continued. The infant was discharged after three months of hospital stay and was later followed up in the plastic surgery unit of the hospital.

Keywords: amnion membrane grafting, autograft, meek technique, newborn, regeneration of skin

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Authors: Morteza Mirhosseini, Amir B. Khoshnevis

Abstract:

The boundary layer separation and new active flow control of a NACA 0025 airfoil were studied experimentally. This new flow control is sometimes known as a co-flow jet (cfj) airfoil. This paper presents the fluctuating velocity in a wall jet over the co-flow jet airfoil subjected to an adverse pressure gradient and a curved surface. In these results, the fluctuating velocity at the inner part increasing by increased the angle of attack up to 12^o and this has due to the jet energized, while the angle of attack 20^o has different. The airfoil cord based Reynolds number has 10⁵.

Keywords: adverse pressure gradient, fluctuating velocity, wall jet, co-flow jet airfoil

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Authors: S. Candamano, A. Iorfida, L. Pagnotta, F. Crea

Abstract:

Basalt fabric reinforced cementitious composites (FRCM) have attracted great attention because they result in being effective in structural strengthening and eco-efficient. In this study, authors investigate their mechanical behavior when an alkali-activated binder, with tuned properties and containing high amounts of industrial by-products, such as ground granulated blast furnace slag, is used. Reinforcement is made up of a balanced, coated bidirectional fabric made out of basalt fibres and stainless steel micro-wire, with a mesh size of 8x8 mm and an equivalent design thickness equal to 0.064 mm. Mortars mixes have been prepared by maintaining constant the water/(reactive powders) and sand/(reactive powders) ratios at 0.53 and 2.7 respectively. Tensile tests were carried out on composite specimens of nominal dimensions equal to 500 mm x 50 mm x 10 mm, with 6 embedded rovings in the loading direction. Direct shear tests (DST), aimed to the stress-transfer mechanism and failure modes of basalt-FRCM composites, were carried out on brickwork substrate using an externally bonded basalt-FRCM composite strip 10 mm thick, 50 mm wide and a bonded length of 300 mm. Mortars exhibit, after 28 days of curing, a compressive strength of 32 MPa and a flexural strength of 5.5 MPa. Main hydration product is a poorly crystalline CASH gel. The constitutive behavior of the composite has been identified by means of direct tensile tests, with response curves showing a tri-linear behavior. The first linear phase represents the uncracked (I) stage, the second (II) is identified by crack development and the third (III) corresponds to cracked stage, completely developed up to failure. All specimens exhibit a crack pattern throughout the gauge length and failure occurred as a result of sequential tensile failure of the fibre bundles, after reaching the ultimate tensile strength. The behavior is mainly governed by cracks development (II) and widening (III) up to failure. The main average values related to the stages are σI= 173 MPa and εI= 0.026% that are the stress and strain of the transition point between stages I and II, corresponding to the first mortar cracking; σu = 456 MPa and εu= 2.20% that are the ultimate tensile strength and strain, respectively. The tensile modulus of elasticity in stage III is EIII= 41 GPa. All single-lap shear test specimens failed due to composite debonding. It occurred at the internal fabric-to-matrix interface, and it was the result of fracture of the matrix between the fibre bundles. For all specimens, transversal cracks were visible on the external surface of the composite and involved only the external matrix layer. This cracking appears when the interfacial shear stresses increase and slippage of the fabric at the internal matrix layer interface occurs. Since the external matrix layer is bonded to the reinforcement fabric, it translates with the slipped fabric. Average peak load around 945 N, peak stress around 308 MPa, and global slip around 6 mm were measured. The preliminary test results allow affirming that Alkali Activated Binders can be considered a potentially valid alternative to traditional mortars in designing FRCM composites.

Keywords: alkali activated binders, basalt-FRCM composites, direct shear tests, structural strengthening

Procedia PDF Downloads 123