Search results for: quantum transport properties

Authors: Juan C. Pérez-Mesa, Emilio Galdeano-Gómez, Jerónimo De Burgos-Jiménez, José F. Bienvenido-Bárcena, José F. Jiménez-Guerrero

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Environmental cost and transport congestion on roads resulting from product distribution in Europe have to lead to the creation of various programs and studies seeking to reduce these negative impacts. In this regard, apart from other institutions, the European Commission (EC) has designed plans in recent years promoting a more sustainable transportation model in an attempt to ultimately shift traffic from the road to the sea by using intermodality to achieve a model rebalancing. This issue proves especially relevant in supply chains from peripheral areas of the continent, where the supply of certain agrifood products is high. In such cases, the most difficult challenge is managing perishable goods. This study focuses on new approaches that strengthen the modal shift, as well as the reduction of externalities. This problem is analyzed by attempting to promote intermodal system (truck and short sea shipping) for transport, taking as point of reference highly perishable products (vegetables) exported from southeast Spain, which is the leading supplier to Europe. Methodologically, this paper seeks to contribute to the literature by proposing a different and complementary approach to establish a comparison between intermodal and the “only road” alternative. For this purpose, the multicriteria decision is utilized in a p-median model (P-M) adapted to the transport of perishables and to a means of shipping selection problem, which must consider different variables: transit cost, including externalities, time, and frequency (including agile response time). This scheme avoids bias in decision-making processes. By observing the results, it can be seen that the influence of the externalities as drivers of the modal shift is reduced when transit time is introduced as a decision variable. These findings confirm that the general strategies, those of the EC, based on environmental benefits lose their capacity for implementation when they are applied to complex circumstances. In general, the different estimations reveal that, in the case of perishables, intermodality would be a secondary and viable option only for very specific destinations (for example, Hamburg and nearby locations, the area of influence of London, Paris, and the Netherlands). Based on this framework, the general outlook on this subject should be modified. Perhaps the government should promote specific business strategies based on new trends in the supply chain, not only on the reduction of externalities, and find new approaches that strengthen the modal shift. A possible option is to redefine ports, conceptualizing them as digitalized redistribution and coordination centers and not only as areas of cargo exchange.

Keywords: environmental externalities, intermodal transport, perishable food, transit time

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Authors: L. Foudia, K. Haddadi, M. Reffas

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First principles study of structural, elastic, electronic and optical properties of the monoclinic perovskite type ScRhO₃ has been reported using the pseudo-potential plane wave method within the local density approximation. The calculated lattice parameters, including the lattice constants and angle β, are in excellent agreement with the available experimental data, which proving the reliability of the chosen theoretical approach. Pressure dependence up to 20 GPa of the single crystal and polycrystalline elastic constants has been investigated in details using the strain-stress approach. The mechanical stability, ductility, average elastic wave velocity, Debye temperature and elastic anisotropy were also assessed. Electronic band structure and density of states (DOS) demonstrated its semiconducting nature showing a direct band gap of 1.38 eV. Furthermore, several optical properties, such as absorption coefficient, reflectivity, refractive index, dielectric function, optical conductivity and electron energy loss function, have been calculated for radiation up to 40 eV.

Keywords: ab-initio, perovskite, DFT, band gap

Procedia PDF Downloads 80

Authors: R. Vasireddi, J. Kruse, M. Vakili, M. Trebbin

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Here we present a gas dynamic virtual nozzle (GDVN) based microfluidic jetting devices for spinning of nano/microfibers. The device is fabricated by soft lithography techniques and is based on the principle of a GDVN for precise three-dimensional gas focusing of the spinning solution. The nozzle device is used to produce micro/nanofibers of a perfluorinated terpolymer (THV), which were collected on an aluminum substrate for scanning electron microscopy (SEM) analysis. The influences of air pressure, polymer concentration, flow rate and nozzle geometry on the fiber properties were investigated. It was revealed that surface properties are controlled by air pressure and polymer concentration while the diameter and shape of the fibers are influenced mostly by the concentration of the polymer solution and pressure. Alterations of the nozzle geometry had a negligible effect on the fiber properties, however, the jetting stability was affected. Round and flat fibers with differing surface properties from craters, grooves to smooth surfaces could be fabricated by controlling the above-mentioned parameters. Furthermore, the formation of surface roughness was attributed to the fast evaporation rate and velocity (mis)match between the polymer solution jet and the surrounding air stream. The diameter of the fibers could be tuned from ~250 nm to ~15 µm. Because of the simplicity of the setup, the precise control of the fiber properties, access to biocompatible nanofiber fabrication and the easy scale-up of parallel channels for high throughput, this method offers significant benefits compared to existing solution-based fiber production methods.

Keywords: gas dynamic virtual nozzle (GDVN) principle, microfluidic device, spinning, uniform nanofibers

Procedia PDF Downloads 150

Authors: Salman Piri

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In this study, a two-dimensional lattice Boltzmann method (LBM) was considered for the numerical simulation of fluid flow in a channel. Also, the Lagrangian method was used for particle tracking in one-way coupling. Three hundred spherical particles with specific diameters were released in the channel entry and an elliptical object was placed in the channel for flow obstruction. The effect of gravity, the drag force, the Saffman lift and the Brownian forces were evaluated in the particle motion trajectories. Also, the effect of the geometrical parameter, ellipse aspect ratio, and the flow characteristic or Reynolds number was surveyed for the transport and deposition of particles. Moreover, the influence of particle diameter between 0.01 and 10 µm was investigated. Results indicated that in small Reynolds, more inertial and gravitational trapping occurred on the obstacle surface for particles with larger diameters. Whereas, for nano-particles, influenced by Brownian diffusion and vortices behind the obstacle, the inertial and gravitational mechanisms were insignificant and diffusion was the dominant deposition mechanism. In addition, in Reynolds numbers larger than 400, there was no significant difference between the deposition of finer and larger particles. Also, in higher aspect ratios of the ellipse, more inertial trapping occurred for particles of larger diameter (10 micrometers), while in lower cases, interception and gravitational mechanisms were dominant.

Keywords: ellipse aspect elito, particle tracking diffusion, lattice boltzman method, larangain particle tracking

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Authors: Reza Sadeghi

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Carbon dioxide treatment is one of the new methods for storage pest control. It can be used to replace chemical approaches for postharvest. Hazelnut has a considerable share in the annual exports of Iran. In the present study, hazelnut was studied after being exposed to different CO2 pressures (0.1-0.5bar) within 24 hours. Changes in organoleptic properties (colour, firmness, aroma, crispness, and overall acceptability) during fumigation were studied. The results showed that the sensory evaluation showed that carbon dioxide had no effect on the qualitative characteristics of hazelnut.

Keywords: carbon dioxide, hazelnut, qualitative characteristics, organoleptic

Procedia PDF Downloads 88

Authors: Muhammad Zaman Khan, Vijay Baheti, Jiri Militky

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The present study is focused on the development of multifunctional cotton fabric while having good physiological comfort properties. The functional properties developed include superhydrophobicity (Lotus effect) and UV protection. For this, TiO₂ nanoparticles along with fluorocarbon and organic-inorganic binder have been used to optimize the multifunctional properties. Deposition of TiO₂ nanoparticles with water repellent finish on cotton fabric has been carried out using the pad dry cure method at fix parameters. The morphology and elemental composition of as-deposited particles have been studied by using SEM and EDS. The chemical composition of nanoparticles was determined using energy dispersive spectroscopy. The treated samples exhibited excellent water repellency and UV protection factor. The study of the comfort properties of fabric showed that it had excellent physiological comfort properties. Optimized concentration of water repellent chemical (50g/l) was used in formulations with TiO₂ nanoparticles and organic-inorganic binder. Four formulations were prepared according to the design of the experiment. The formulations were applied to the cotton fabric by roller padding at room temperature (15–20°C). Surface morphology was investigated via SEM images. EDS analysis was also carried out to analyze the composition and atomic percentage of elements. The water contact angle (WCA) of cotton fabric increases with increase in TiO₂ nanoparticles concentration and reaches its maximum value (157°) when the concentration of TiO₂ is 20g/l. The water sliding angle (WSA) decreases and gains minimum value at the same concentration of TiO₂ at which WCA is highest. It was seen samples treated with formulations of TiO₂ nanoparticles exhibits excellent UPF, UV-A and UV-B blocking. However, there was no significant deterioration of air permeability. The water vapor permeability was also slightly decreased (4%) but is acceptable. It can be concluded that there is no significant change in both air and water vapor permeability after nanoparticles coating on the surface of the cotton fabric. The coated cotton fabric has little effect on the stiffness. The stiffness of coated samples was not increased significantly; thus comfort of cotton fabric is not decreased. This functionalized cotton fabric also exhibits good physiological comfort properties. ''The authors are also thankful to student grant competition 21312 provided at Technical University of Liberec''.

Keywords: comfort, functional, nanoparticles, UV protective

Procedia PDF Downloads 145

Authors: S. Assylbekova, D. Zolotareva, A. Dauletbakov, Ye. Belyankova, S. Bayazit, A. Basharimova, A. Zazybin, A. Isimberlenova, A. Kakimova, M. Aydemir, A. Kairullinova

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Transfer hydrogenation (TH) is a key process in organic chemistry, especially in pharmaceutical and agrochemical synthesis, offering a safer and more sustainable approach compared to traditional methods. This work is devoted to the synthesis and use of ruthenium catalysts containing phosphinite ligands in TH reactions. Ruthenium complexes are particularly noteworthy for their effectiveness in asymmetric TH. Their stability and adaptability to different reaction environments make them ideal for both laboratory-scale and industrial applications. Phosphinite ligands (P(OR)R'2) are used in the synthesis of complexes to improve their properties. These ligands are known for their ability to finely tune the electronic and steric properties of metal centers. The electron-donating nature of the phosphorus atom, combined with the variability in the R and R' groups, allows for significant customization of the catalyst's properties. The purpose and difference of the work is to study the incorporation of a hydrophilic ionic liquid into the composition of a phosphinite ligand, which will then be converted into a catalyst. The technique involves the synthesis of a phosphinite ligand with an ionic liquid at room temperature under an inert atmosphere and then a ruthenium complex. Next, the TH reactions of acetophenone and its derivatives are carried out using the resulting catalyst. The conversion of ketone to alcohol is analyzed using a gas chromatograph. This study contributes to the understanding of the influence of catalyst physico-chemical properties on transfer hydrogenation results.

Keywords: transfer hydrogenation, ruthenium, catalysts, phosphinite ligands

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Authors: Taiwo Olusoji Lawrence, Peace Mawo Aaron

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Seismic analysis of bedforms has proven to be one of the best ways to study deepwater sedimentary features. Canyons are known to be sediment transportation conduit. Sediment wave are large-scale depositional bedforms in various parts of the world's oceans formed predominantly by suspended load transport. These undulating objects usually have tens of meters to a few kilometers in wavelength and a height of several meters. Cyclic steps have long long-wave upstream-migrating bedforms confined by internal hydraulic jumps. They usually occur in regions with high gradients and slope breaks. Cyclic steps and migrating sediment waves are the most common bedform on the seafloor. Cyclic steps and related sediment wave bedforms are significant to the morpho-dynamic evolution of deep-water depositional systems architectural elements, especially those located along tectonically active margins with high gradients and slope breaks that can promote internal hydraulic jumps in turbidity currents. This report examined sedimentary activities and sediment transportation in submarine canyons and provided distinctive insight into factors that created a complex seabed canyon system in the Ceara Fortaleza basin Brazilian Equatorial Margin (BEM). The growing importance of cyclic steps made it imperative to understand the parameters leading to their formation, migration, and architecture as well as their controls on sediment transport in canyon thalweg. We extracted the parameters of the observed bedforms and evaluated the aspect ratio and asymmetricity. We developed a relationship between the hydraulic jump magnitude, depth of the hydraulic fall and the length of the cyclic step therein. It was understood that an increase in the height of the cyclic step increases the magnitude of the hydraulic jump and thereby increases the rate of deposition on the preceding stoss side. An increase in the length of the cyclic steps reduces the magnitude of the hydraulic jump and reduces the rate of deposition at the stoss side. Therefore, flat stoss side was noticed at most preceding cyclic step and sediment wave.

Keywords: Ceara Fortaleza, submarine canyons, cyclic steps, sediment wave

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Authors: Catalin Croitoru, Ionut Claudiu Roata

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Employing concentrated solar energy (CSE) for sintering metallic parts offers distinct advantages, notably in the rapid thermal cycling that significantly influences their microstructure and phase transitions. This study uses the thermal control that CSE affords, enhancing the mechanical properties and tailoring the functionality of nickel-based alloys. We synthesized bulk alloys by sintering Ni-Cr-Al-Y powders in varied ratios using a vertical solar furnace at PROMES-CNRS, Font-Romeu Odeillo, France. The process achieved optimal fusion at 800°C for 10 minutes, resulting in materials with a notable hydrophilic surface due to oxide formation. The alloys’ performance was evaluated through corrosion resistance tests in a 3.5% wt. NaCl solution, utilizing potentiodynamic scanning and electrochemical impedance spectroscopy. Our findings demonstrate the potential of CSE in advancing the material properties of nickel-based alloys for diverse applications.

Keywords: concentrated solar energy, sintering, corrosion resistance, surface properties

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Authors: M. Khalid, W. Rashmi, L. L. Kwan

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This work provides an overview on the experimental and numerical simulations of various nanofluids and their flow and heat transfer behavior. It was further extended to study the effect of nanoparticle concentration, fluid flow rates and thermo-physical properties on the heat transfer enhancement of Al2O3/water nanofluid in a turbulent flow circular conduit using ANSYS FLUENT™ 14.0. Single-phase approximation (homogeneous model) and two-phase (mixture and Eulerian) models were used to simulate the nanofluid flow behavior in the 3-D horizontal pipe. The numerical results were further validated with experimental correlations reported in the literature. It was found that heat transfer of nanofluids increases with increasing particle volume concentration and Reynolds number, respectively. Results showed good agreement (~9% deviation) with the experimental correlations, especially for a single-phase model with constant properties. Among two-phase models, mixture model (~14% deviation) showed better prediction compared to Eulerian-dispersed model (~18% deviation) when temperature independent properties were used. Non-drag forces were also employed in the Eulerian two-phase model. However, the two-phase mixture model with temperature dependent nanofluid properties gave slightly closer agreement (~12% deviation).

Keywords: nanofluid, CFD, heat transfer, forced convection, circular conduit

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Authors: Mahmoud M. Tash, S. Alkahtani

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The present study was undertaken to investigate the effect of pre-aging and aging parameters (time and temperature) on the mechanical properties of Al-Mg-Zn (7075) alloys. Ultimate tensile strength, 0.5% offset yield strength and % elongation measurements were carried out on specimens prepared from cast and heat treated 7075 alloys. Aging treatments were carried out for the as solution treated (SHT) specimens (after quenching in warm water). The specimens were aged at different conditions; Natural aging was carried out at room temperature for different periods of time. Double aging was performed for SHT conditions (pre-aged at different time and temperature followed by high temperature aging). Ultimate tensile strength, yield strength and % elongation as a function of different pre-aging and aging parameters are analysed to acquire an understanding of the effects of these variables and their interactions on the mechanical properties of Be-treated 7075 alloys.

Keywords: duplex aging treatment, mechanical properties, Al-Mg-Zn (7075) alloys, manufacturing

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Authors: Kar Lin Nyam, Phey Yee Lim

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The aim of this study was to determine the antioxidant potential, nutritional composition, and functional properties of kenaf leaves powder. Besides, the effect of kenaf leaves powder in bread qualities, properties, and consumer acceptability were evaluated. Different formulations of bread fortified with 0%, 4% and 8% kenaf leaves powder, respectively were produced. Physical properties of bread, such as loaf volume, dough expansion, crumb colour, and bread texture, were determined. Nine points hedonic scale was utilized in sensory evaluation to determine the best formulation (the highest overall acceptability). Proximate composition, calcium content, and antioxidant properties were also determined for the best formulation. 4% leaves powder bread was the most preferred by the panelists followed by control bread, and the least preferred was being 8% leaves powder bread. 4% leaves powder bread had significantly higher value of DPPH radical scavenging capacity (8.05 mg TE/100g), total phenolic content (12.88 mg GAE/100g) and total flavonoid content (13.26 mg QE/100g) compared to control bread (1.38 mg TE/100g, 8.17 mg GAE/100g, and 8.77 mg QE/100g respectively). Besides, 4% leaves powder bread also showed higher in calcium content and total dietary fiber compared to control bread. Kenaf leaves powder is suitable to be used as a source of natural antioxidant for fortification and nutrient improver in bread.

Keywords: dietary fibre, calcium, total phenolic content, total flavonoid content

Procedia PDF Downloads 127

Authors: M. A. Izzati, R. Rosazley, A. W. Fareezal, M. Z. Shazana, I. Rushdan, M. Jani

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Ultrasonic probe were using to produce nanofibrillated cellulose (NFC) kenaf core. NFC kenaf core and graphene was mixed using in-situ method with the 5V voltage for 24 hours. The resulting NFC graphene paper was characterized by field emission scanning electron microscopy (FESEM), fourier transformed infrared (FTIR) spectra and thermogavimetric analysis (TGA). The properties of NFC kenaf core graphene paper are compared with properties of pure NFC kenaf core paper.

Keywords: NFC, kenaf core, graphene, in-situ method

Procedia PDF Downloads 394

Authors: Aynur Aker, Hasan Kaya

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In recent years, the use of the aluminum based alloys in the industry and technology are increasing. Alloying elements in aluminum have further been improving the strength and stiffness properties that provide superior compared to other metals. In this study, investigation of physical properties (microstructure, microhardness, tensile strength, electrical conductivity and thermal properties) in the Al-12.6wt.%Si-%2wt.Ni ternary alloy were investigated. Al-Si-Ni alloy was prepared in a graphite crucible under vacuum atmosphere. The samples were directionally solidified upwards with different growth rate (V) at constant temperature gradient G (7.73 K/mm). The microstructures (flake spacings, λ), microhardness (HV), ultimate tensile strength, electrical resistivity and thermal properties enthalpy of fusion and specific heat and melting temperature) of the samples were measured. Influence of the growth rate and flake spacings on microhardness, ultimate tensile strength and electrical resistivity were investigated and relationships between them were experimentally obtained by using regression analysis. According to results, λ values decrease with increasing V, but microhardness, ultimate tensile strength, electrical resistivity values increase with increasing V. Variations of electrical resistivity for cast samples with the temperature in the range of 300-1200 K were also measured by using a standard dc four-point probe technique. The enthalpy of fusion and specific heat for the same alloy was also determined by means of differential scanning calorimeter (DSC) from heating trace during the transformation from liquid to solid. The results obtained in this work were compared with the previous similar experimental results obtained for binary and ternary alloys.

Keywords: electrical resistivity, enthalpy, microhardness, solidification, tensile stress

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Authors: Mahdi Amne Elahi, Marcus Koch, Peter Plapper

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Due to the demand of miniaturizing in automotive industry, the application of laser welding is quite promising. The current study focused on laser micro-welding of CuSn6 bronze and nickel wire for a miniature electromechanical hybrid component. Due to the advantages of laser welding, the welding can be tailored specifically for the requirements of the part. Scanning electron and optical microscopy were implemented to study the microstructure and tensile-shear test was selected to represent the mechanical properties. Different welding sides, beam oscillations, and speeds have been investigated to optimize the tensile-shear load and microstructure. The results show that the mechanical properties and microstructure of the joint is highly under the influence of the mentioned parameters. Due to the lack of intermetallic compounds, the soundness of the joint is achievable by manipulating the geometry of the weld seam and minimize weld defects.

Keywords: bronze, laser micro-welding, microstructure, nickel, tensile shear test

Procedia PDF Downloads 166

Authors: Usoro Anthony E., Udoh Emediong

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Diagonal Vector Autoregressive Models are special classes of the general vector autoregressive models identified under certain conditions, where parameters are restricted to the diagonal elements in the coefficient matrices. Variance, autocovariance, and autocorrelation properties of the upper and lower diagonal VAR models are derived. The new set of VAR models is verified with empirical data and is found to perform favourably with the general VAR models. The advantage of the diagonal models over the existing models is that the new models are parsimonious, given the reduction in the interactive coefficients of the general VAR models.

Keywords: VAR models, diagonal VAR models, variance, autocovariance, autocorrelations

Procedia PDF Downloads 116

Authors: S. Assengone Otogo Be, A. Fahs, L. Belec, T. A. Nguyen Tien, G. Louarn, J-F. Chailan

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Glass fiber-reinforced composite materials have gradually developed in all sectors ranging from consumer products to aerospace applications. However, the weak point is most often the fiber/matrix interface, which can reduce the durability of the composite material. To solve this problem, it is essential to control the interphase and improve our understanding of the adhesion mechanism at the fibre/matrix interface. The interphase properties depend on the nature of the sizing applied on the surface of the glass fibers during their manufacture in order to protect them, facilitate their handling, and ensure fibre/matrix adhesion. The sizing composition, and in particular the nature of the coupling agent and the film-former affects the mechanical properties and the durability of composites. The aim of our study is, therefore, to develop and study composite materials with simplified sizing systems in order to understand how the main constituents modify the mechanical properties and the durability of composites from the nanometric to the macroscopic scale. Two model systems were elaborated: an epoxy matrix reinforced with simplified-sized glass fibres and an epoxy coating applied on glass substrates treated with the same sizings as fibres. For the sizing composition, two configurations were chosen. The first configuration possesses a chemical reactivity to link the glass and the matrix, and the second sizing contains non-reactive agents. The chemistry of the sized glass substrates and fibers was analyzed by FT-IR and XPS spectroscopies. The surface morphology was characterized by SEM and AFM microscopies. The observation of the surface samples reveals the presence of sizings which morphology depends on their chemistry. The evaluation of adhesion of coated substrates and composite materials show good interfacial properties for the reactive configuration. However, the non-reactive configuration exhibits an adhesive rupture at the interface of glass/epoxy for both systems. The interfaces and interphases between the matrix and the substrates are characterized at different scales. Correlations are made between the initial properties of the sizings and the mechanical performances of the model composites.

Keywords: adhesion, interface, interphase, materials composite, simplified sizing systems, surface properties

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Authors: Yulna Yulnafatmawita, Syafrimen Yasin, Lusi Maira

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Irrigation source is one of the factors affecting physical properties of rice field. This research was aimed to determine the impact of polluted irrigation wáter on soil physical properties of rice field. The study site was located in Koto Nan IV, Dharmasraya Regency, West Sumatra, Indonesia. The rice field was irrigated with wáter from Momongan river in which people do gold mining. The soil was sampled vertically from the top to 100 cm depth with 20 cm increment of soil profile from 2 year-fallowed rice field, as well as from the top 20 cm of cultivated rice field from the terrace-1 (the highest terrace) to terrace-5 (the lowest terrace) position. Soil samples were analysed in laboratory. For comparison, rice field receiving irrigation wáter from non-polluted source was also sampled at the top 20 cm and anaysed for the physical properties. The result showed that there was a change in soil physical properties of rice field after 9 years of getting irrigation from the river. Based on laboratory analyses, the total suspended solid (TSS) in the tailing reached 10,736 mg/L. The texture of rice field at polluted rice field (PRF) was dominated (>55%) by sand particles at the top 100 cm soil depth, and it tended to linearly decrease (R2=0.65) from the top 20 cm to 100 cm depth. Likewise, the sand particles also linearly decreased (R2=0.83), but clay particles linearly increased (R2=0.74) horizontally as the distance from the wáter input (terrace-1) was fartherst. Compared to nonpolluted rice field (NPRF), percentage of sand was higher, and clay was lower at PRF. This sandy texture of soil in PRF increased soil hydraulic conductivity (up to 19.1 times), soil bulk density (by 38%), and sharply decreased SOM (by 88.5 %), as well as soil total pore (by 22.1%) compared to the NPRF at the top 20 cm soil. The rice field was suggested to be reclaimed before reusing it. Otherwise the soil characteristics requirement, especially soil wáter retention, for rice field could not be fulfilled.

Keywords: gold mine tailing, polluted irrigation, rice field, soil physical properties

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Authors: Lalita, Niladri Sarkar, Subhasis Ghosh

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Since the discovery of high temperature superconductivity (HTSC) in cuprates, several aspects of this phenomena have fascinated physics community. The most debated one is the linear temperature dependence of normal state resistivity over wide range of temperature in violation of with Fermi liquid theory. The linear-in-T resistivity (LITR) is the indication of strongly correlated metallic, known as “strange metal”, attributed to non Fermi liquid theory (NFL). The proximity of superconductivity to LITR suggests that there may be underlying common origin. The LITR has been shown to be due to unknown dissipative phenomena, restricted by quantum mechanics and commonly known as ‘‘Planckian dissipation” , the term first coined by Zaanen and the associated inelastic scattering time τ and given by 1/τ=αkBT/ℏ, where ℏ, kB and α are reduced Planck’s constant, Boltzmann constant and a dimensionless constant of order of unity, respectively. Since the first report, experimental support for α ~ 1 is appearing in literature. There are several striking issues which remain to be resolved if we desire to find out or at least get a clue towards microscopic origin of maximal dissipation in cuprates. (i) Universality of α ~ 1, recently some doubts have been raised in some cases. (ii) So far, Planckian dissipation has been demonstrated in overdoped Cuprates, but if the proximity to quantum criticality is important, then Planckian dissipation should be observed in optimally doped and marginally underdoped cuprates. The link between Planckian dissipation and quantum criticality still remains an open problem. (iii) Validity of Planckian dissipation in all cuprates is an important issue. Here, we report reversible change in the superconducting behavior of high temperature superconductor Bi2Sr2Ca2Cu3O10+δ (Bi-2223) under dynamic doping induced by photo-excitation. Two doped Bi-223 samples, which are x = 0.16 (optimal-doped), x = 0.145 (marginal-doped) have been used for this investigation. It is realized that steady state photo-excitation converts magnetic Cu2+ ions to nonmagnetic Cu1+ ions which reduces superconducting transition temperature (Tc) by killing superfluid density. In Bi-2223, one would expect the maximum of suppression of Tc should be at charge transfer gap. We have observed suppression of Tc starts at 2eV, which is the charge transfer gap in Bi-2223. We attribute this transition due to Cu-3d9(Cu2+) to Cu-3d10(Cu+), known as d9 − d10 L transition, photoexcitation makes some Cu ions in CuO2 planes as spinless non-magnetic potential perturbation as Zn2+ does in CuO2 plane in case Zn-doped cuprates. The resistivity varies linearly with temperature with or without photo-excitation. Tc can be varied by almost by 40K be photoexcitation. Superconductivity can be destroyed completely by introducing ≈ 2% of Cu1+ ions for this range of doping. With this controlled variation of Tc and resistivity, detailed investigation has been carried out to reveal Planckian dissipation underdoped to optimally doped Bi-2223. The most important aspect of this investigation is that we could vary Tc dynamically and reversibly, so that LITR and associated Planckian dissipation can be studied over wide ranges of Tc without changing the doping chemically.

Keywords: linear resistivity, HTSC, Planckian dissipation, strange metal

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Authors: Yousef S. Kh. S. Hashem

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Accurate estimation of initial gas in place (IGIP) plays an important factor in the decision to develop a gas field. One of the methods that are available in the industry to estimate the IGIP is material balance. This method required that the well has to be shut-in while pressure is measured as it builds to average reservoir pressure. Since gas demand is high and shut-in well surveys are very expensive, flowing gas material balance (FGMB) is sometimes used instead of material balance. This work investigated the effect of reservoir properties (pressure, permeability, and reservoir size) on the estimation of IGIP when using FGMB. A gas reservoir simulator that accounts for friction loss, wellbore storage, and the non-Darcy effect was used to simulate 165 different possible causes (3 pressures, 5 reservoir sizes, and 11 permeabilities). Both tubing pressure and bottom-hole pressure were analyzed using FGMB. The results showed that the FGMB method is very sensitive for tied reservoirs (k < 10). Also, it showed which method is best to be used for different reservoir properties. This study can be used as a guideline for the application of the FGMB method.

Keywords: flowing material balance, gas reservoir, reserves, gas simulator

Procedia PDF Downloads 155

Authors: Jonggeon Lee, Sungho Tae, Sungjoon Suk, Keunhyeok Yang, George Ford, Michael E. Smith, Omidreza Shoghli

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In recent years, research to reduce carbon emissions through quantitative assessment of building life cycle carbon emissions has been performed as it relates to the construction industry. However, most research efforts related to building carbon emissions assessment have been focused on evaluation during the operational phase of a building’s life span. Few comprehensive studies of the carbon emissions during a building’s construction phase have been performed. The purpose of this study is to propose an assessment method that quantitatively evaluates the carbon emissions of buildings during the construction phase. The study analysed the amount of carbon emissions produced by 17 construction trades, and selected four construction trades that result in high levels of carbon emissions: reinforced concrete work; sheathing work; foundation work; and form work. Building materials, and construction and transport equipment used for the selected construction trades were identified, and carbon emissions produced by the identified materials and equipment were calculated for these four construction trades. The energy consumption of construction and transport equipment was calculated by analysing fuel efficiency and equipment productivity rates. The combination of the expected levels of carbon emissions associated with the utilization of building materials and construction equipment provides means for estimating the quantity of carbon emissions related to the construction phase of a building’s life cycle. The proposed carbon emissions assessment method was validated by case studies.

Keywords: building construction phase, carbon emissions assessment, building life cycle

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Authors: Wei Quan, Liu Chao, Mohammed N. Afsar

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The dielectric properties and ionic conductivity of novel "ceramic state" polymer electrolytes for high capacity lithium battery are characterized by radio-frequency and Microwave methods in two broad frequency ranges from 50 Hz to 20 KHz and 4 GHz to 40 GHz. This innovative solid polymer electrolyte which is highly ionic conductive (10-3 S/cm at room temperature) from -40 oC to +150 oC and can be used in any battery application. Such polymer exhibits properties more like a ceramic rather than polymer. The various applied measurement methods produced accurate dielectric results for comprehensive analysis of electrochemical properties and ion transportation mechanism of this newly invented polymer electrolyte. Two techniques and instruments employing air gap measurement by capacitance bridge and inwave guide measurement by vector network analyzer are applied to measure the complex dielectric spectra. The complex dielectric spectra are used to determine the complex alternating current electrical conductivity and thus the ionic conductivity.

Keywords: polymer electrolyte, dielectric permittivity, lithium battery, ionic relaxation, microwave measurement

Procedia PDF Downloads 478

Authors: Emmanuel Okechukwu Nwafor, Folake Olubunmi Akintayo, Denis Alcides Rezende

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Decision tree models are versatile and interpretable machine learning algorithms widely used for both classification and regression tasks, which can be related to cities, whether physical or digital. The aim of this research is to assess how well decision tree algorithms can predict trip purposes in Makurdi, Nigeria, while also exploring their connection to the strategic digital city initiative. The research methodology involves formalizing household demographic and trips information datasets obtained from extensive survey process. Modelling and Prediction were achieved using Python Programming Language and the evaluation metrics like R-squared and mean absolute error were used to assess the decision tree algorithm's performance. The results indicate that the model performed well, with accuracies of 84% and 68%, and low MAE values of 0.188 and 0.314, on training and validation data, respectively. This suggests the model can be relied upon for future prediction. The conclusion reiterates that This model will assist decision-makers, including urban planners, transportation engineers, government officials, and commuters, in making informed decisions on transportation planning and management within the framework of a strategic digital city. Its application will enhance the efficiency, sustainability, and overall quality of transportation services in Makurdi, Nigeria.

Keywords: decision tree algorithm, trip purpose, intelligent transport, strategic digital city, travel pattern, sustainable transport

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Authors: Xinghui Wu, Chun Yang

Abstract:

Inertial microfluidics is a competitive fluidic method with applications in separation of particles, cells and bacteria. In contrast to traditional microfluidic devices with low Reynolds number, inertial microfluidics works in the intermediate Re number range which brings about several intriguing inertial effects on particle separation/focusing to meet the throughput requirement in the real-world. Geometric modifications to make channels become irregular shapes can leverage fluid inertia to create complex secondary flow for adjusting the particle equilibrium positions and thus enhance the separation resolution and throughput. Although inertial microfluidics has been extensively studied by experiments, our current understanding of its mechanisms is poor, making it extremely difficult to build rational-design guidelines for the particle focusing locations, especially for irregularly shaped microfluidic channels. Inertial particle microfluidics in irregularly shaped channels were investigated in our group. There are several fundamental issues that require us to address. One of them is about the balance between the inertial lift forces and the secondary drag forces. Also, it is critical to quantitatively describe the dependence of the life forces on particle-particle interactions in irregularly shaped channels, such as a rectangular one. To provide physical insights into the inertial microfluidics in channels of irregular shapes, in this work the immersed boundary-lattice Boltzmann method (IB-LBM) was introduced and validated to explore the transport characteristics and the underlying mechanisms of an inertial focusing single particle in a rectangular microchannel. The transport dynamics of a finitesized particle were investigated over wide ranges of Reynolds number (20 < Re < 500) and particle size. The results show that the inner equilibrium positions are more difficult to occur in the rectangular channel, which can be explained by the secondary flow caused by the presence of a finite-sized particle. Furthermore, force decoupling analysis was utilized to study the effect of each type of lift force on the inertia migration, and a theoretical model for the lateral lift force of a finite-sized particle in the rectangular channel was established. Such theoretical model can be used to provide theoretical guidance for the design and operation of inertial microfluidics.

Keywords: inertial microfluidics, particle focuse, life force, IB-LBM

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Authors: Qaiser uz Zaman Khan

Abstract:

This research article provides a comprehensive study of combining steel fiber and polypropylene fibers in concrete at different mix ratios. This blending of various fibers has led to the development of hybrid fiber-reinforced concrete (HFRC), which offers notable improvements in mechanical properties and increased resistance to cracking. Steel fibers are known for their high tensile strength and excellent crack control abilities, while polypropylene fibers offer increased toughness and impact resistance. The synergistic use of these two fiber types in concrete has yielded promising outcomes, effectively enhancing its overall performance. This article explores the key aspects of hybridization, including fiber types, proportions, mixing methods, and the resulting properties of the concrete. Additionally, challenges, potential applications, and future research directions in the field are discussed.

Keywords: FRC, fiber-reinforced concrete, split tensile testing, HFRC, mechanical properties, steel fibers, reinforced concrete, polypropylene fibers

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Authors: Erfan Asghari Fesaghandis, Reza Ghaffari Adli, Abbas Kianvash, Hossein Aghajani, Homa Homaie

Abstract:

NiTi alloys possess magnificent superelastic, shape memory, high strength and biocompatible properties. For improving mechanical properties, foremost, superelasticity behavior, heat treatment process is carried out. In this paper, two different heat treatment methods were undertaken: (1) solid solution, and (2) aging. The effect of each treatment in a constant time is investigated. Five samples were prepared to study the structure and optimize mechanical properties under different time and temperature. For measuring the upper plateau stress, lower plateau stress and residual strain, tensile test is carried out. The samples were aged at two different temperatures to see difference between aging temperatures. The sample aged at 500 °C has a bigger crystallite size and lower amount of Ni which causes the mentioned sample to possess poor pseudo elasticity behaviour than the other aged sample. The sample aged at 460 °C has shown remarkable superelastic properties. The mentioned sample’s higher plateau is 580 MPa with the lowest residual strain (0.17%) while other samples have possessed higher residual strains. X-ray diffraction was used to investigate the produced phases.

Keywords: heat treatment, phase transformation, superelasticity, NiTi alloy

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Authors: Anton V. Doroshin

Abstract:

This article contains a description of main ideas for the attitude reorientation of spacecraft (small dual-spin spacecraft, nanosatellites) using properties of its chaotic attitude motion under the action of internal perturbations. The considering method based on intentional initiations of chaotic modes of attitude motion with big amplitudes of the nutation oscillations, and also on the redistributions of the angular momentum between coaxial bodies of the dual-spin spacecraft (DSSC), which perform in the purpose of system’s phase space changing.

Keywords: spacecraft, attitude dynamics, control, chaos

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Authors: Nurudeen Ayeni, Kasali Bello, Ovi Abayeh

Abstract:

Study of the effect of dye–resin complexation on the degree of dye absorption were carried out using Procion Blue MX-R to dye cotton fabric in the presence hexamethylol melamine (MR 6) and its phosphate derivative (MPR 4) for resination. The highest degree of dye exhaustion was obtained at 400 C for 1 hour with the resinated fabric showing more affinity for the dye than the ordinary fiber. Improved fastness properties was recorded which show a relatively higher stability of dye–resin–cellulose network formed.

Keywords: cotton fabric, reactive dye, dyeing, resination

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Authors: Samar Aoujia, Théo Guérineaub, Rayan Zaitera, Evelyne Fargina, Younès Messaddeqb, Thierry Cardinala

Abstract:

Two barium gallo-germanate glass series were elaborated to investigate the effect of the yttrium introduction on the glass physicochemical properties and crystallization behavior. One to twenty mol% of YO3/2 were either added into the glass matrix or substituted for gallium oxide. The glass structure was studied by Raman spectroscopy, and the thermal, optical, thermo-mechanical and physical properties are examined. The introduction of yttrium ions in both glass series increases the glass transition temperature, crystallization temperature, softening temperature, coefficient of linear thermal expansion and density. Through differential scanning calorimetry and X-ray diffraction analyses, it was found that competition occurs between the gallo-germanate zeolite-type phase and the yttrium-containing phase. From 13 mol% of YO3/2, the yttrium introduction impedes the formation of surface crystallization in these glasses.

Keywords: photonic, heavy-metal oxide, glass, crystallization

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Authors: Hussein M. Elmehdi

Abstract:

In this paper, we present the results of our recent experiments done to examine the effect of air bubbles, which were introduced to bio-samples during preparation, on the rheological properties of soft biological materials. To effectively achieve this, we three samples each prepared with differently. Our soft biological systems comprised of three types of flour dough systems made from different flour varieties with variable protein concentrations. The samples were investigated using ultrasonic waves operated at low frequency in transmission mode. The sample investigated included dough made from bread flour, wheat flour and all-purpose flour. During mixing, the main ingredient of the samples (the flour) was transformed into cohesive dough comprised of the continuous dough matrix and air pebbles. The rheological properties of such materials determine the quality of the end cereal product. Two ultrasonic parameters, the longitudinal velocity and attenuation coefficient were found to be very sensitive to properties such as the size of the occluded bubbles, and hence have great potential of providing quantitative evaluation of the properties of such materials. The results showed that the magnitudes of the ultrasonic velocity and attenuation coefficient peaked at optimum mixing times; the latter of which is taken as an indication of the end of the mixing process. There was an agreement between the results obtained by conventional rheology and ultrasound measurements, thus showing the potential of the use of ultrasound as an on-line quality control technique for dough-based products. The results of this work are explained with respect to the molecular changes occurring in the dough system as the mixing process proceeds; particular emphasis is placed on the presence of free water and bound water.

Keywords: ultrasound, soft biological materials, velocity, attenuation

Procedia PDF Downloads 277