Search results for: star formation rate

Authors: Zineb Benouahmane, Zhang Lifeng

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Experimental oxidation tests at high temperature (1300°C-1500°C) on α-SiC samples have been performed with different holding times and atmosphere (air, argon). Oxidized samples were then analyzed using X-ray photoelectron spectroscopy coupled to SEM and DAKTEK surface profiler verification. The oxidation rate and the mas gain were found to increase with temperature and holding times, corresponding to a passive oxidation regime which lead to the formation of SiO2 layer. The sessile drop method is employed in order to measure the wetting angles between Si/SiC system at high temperature (1430°C-1550°C). Contact angle can be varied between 44 °C to 85°C, by controlling the oxygen content in α-SiC. Increasing the temperature occurred the infiltration of liquid silicon and deoxidation of the coating.

Keywords: oxidation, wettability, silicon, SiC

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Authors: Sayyed Mohammed Rafi

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Phytolith studies were carried out for the intrabasaltic bole beds occurring in the western part of the Deccan Volcanic Province. This preliminary study indicates the presence of multiform phytoliths both in red and green boles. Red bole indicates well preserved elongate phytoliths from Acanthaceae plants while bulky Bulliform phytoliths mainly from Pleioblastus/ Andropogonea/reeds plants. Degeneration of few phytoliths from red bole indicates either leaching/etching or some other activity that is responsible for such post-preservation conditions. Phytoliths from the green bole, however, seem to be well preserved as compared to those from the red bole. The phytoliths from green bole are mainly of Festucoid types (especially small square and rectangular types) indicating the presence of Chrysobalanaceae type of vegetation followed by elongate phytoliths from Acanthaceae plant types. The Multiform Trichomes seems to be derived from Panicoid/Andropogonoid/Burseraceae/Fabaceae while Bulliforms from Pleioblastus/Andropogonea/reeds. Presences of silicified woody elements from both red and green boles indicate the presence of dicotyledonous plants which could have been in the form of small shrubs. The degenerated phytoliths in red bole suggest leaching/etching or higher intensity of weathering suggesting the existence of well-drained conditions during its formation that enhanced the leaching activity while the presence of well-preserved phytoliths in green bole point towards the existence of damp and desiccated conditions during its formation. The prevalence of dry condition during red bole formation could suggest their formation under higher temperature as compared to green bole. Based on the phytolith analysis it is too early to comment on the palaeoclimates which could have prevailed during the bole bed formations. However a detailed micromorphological, as well as phytolith analysis of more samples, can throw light on the palaeoenvironmental conditions as well as the biological activity during their formation.

Keywords: Deccan volcanic province, intrabasaltic bole beds, palaeoclimate, phytoliths

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Authors: A. Mohamed, A. El-Aziz

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The pH of the body plays a great role in the degradation kinetics of biodegradable Mg-Ca orthopedic implants. At the location of fracture, the pH of the body becomes no longer neutral which draws the attention towards studying a range of different pH values of the body fluid. In this study, the pH of Hank’s balanced salt solution (HBSS) was modified by phosphate buffers into an aggressive acidic pH 1.8, a slightly acidic pH 5.3 and an alkaline pH 8.1. The biodegradation of Mg-0.8Ca implant was tested in those three different media using immersion test and electrochemical polarization means. It was proposed that the degradation rate has increased with decreasing the pH of HBSS. The immersion test revealed weight gain for all the samples followed by weight loss as the immersion time increased. The highest weight gain was pronounced for the acidic pH 1.8 and the least weight gain was observed for the alkaline pH 8.1. This was in agreement with the electrochemical polarization test results where the degradation rate was found to be high (7.29 ± 2.2 mm/year) in the aggressive acidic solution of pH 1.8 and relatively minimum (0.31 ± 0.06 mm/year) in the alkaline medium of pH 8.1. Furthermore, it was confirmed that the pH of HBSS has reached a steady state of an alkaline pH (~pH 11) at the end of the two-month immersion period regardless of the initial pH of the solution. Finally, the corrosion products formed on the samples’ surface were investigated by SEM, EDX and XRD analyses that revealed the formation of magnesium and calcium phosphates with different morphologies according to the pH.

Keywords: biodegradable, electrochemical polarization means, orthopedics, immersion test, simulated body fluid

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Authors: Khizar Samiullah, Khurram Faroz, Riffat Yasin, Mehwish Iftekhar, Saleem Akhtar

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The fossil site Lava is highly fossiliferous locality in the Chinji Formation, Lower Siwalik Hills of Pakistan. The studied mammalian fossil fauna from this locality consists of Suids, Giraffids and Bovids. The presence of these groups indicates that this Miocene locality has age of approximately 14-11 Ma. Sedimentologically this site is characterized by sandstone and reddish shale which also represents Chinji Formation of the Siwaliks, it consists of shales, siltstones, sandstones and there sediments show large variations in their degree of cementation. Few scientists worked at this locality, as it was first time discovered in 2011. The outcrops of lava locality were selected to explore in detail and comparison with European mammalian assemblages. The main focus was on artiodactyl’s mammalian fauna and four different species have been recovered during field work, in which Giraffokeryx punjabiensis is dominant. Different aspect like biogeographic distribution, evolution and taxonomy of discovered fossils fauna has been discussed in detail in this research work.

Keywords: fossil remains, lava, Chinji Formation, Pakistan

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Authors: Khaled Albriki, Feiyu Wang

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The failed rifted epicratonic Sirt basin is located in the northern margin of the African Plate with an area of approximately 600,000 km2. The organofacies' classification, characterization, and its distribution vertically and horizontally are carried out in 7 main troughs with 32 typical selected wells. 7 geological and geochemical cross sections including Rock-Eval data and % TOC data are considered in order to analyze and to characterize the main organofacies with respect to their geochemical and geological controls and also to remove the ambiguity behind the complexity of the orgnofacies types and distributions in the basin troughs from where the oil and gas are generated and migrated. This study confirmes that there are four different classical types of organofacies distributed in Sirt basin F, D/E, C, and B. these four clasical types of organofacies controls the type and amount of the hydrocarbon discovered in Sirt basin. Oil bulk property data from more than 20 oil and gas fields indicate that D/E organoface are significant oil and gas contributors similar to B organoface. In the western Sirt basin in Zallah-Dur Al Abd, Hagfa, Kotla, and Dur Atallha troughs, F organoface is identified for Etel formation, Kalash formation and Hagfa formation having % TOC < 0.6, whereas the good quality D/E and B organofacies present in Rachmat formation and Sirte shale formation both have % TOC > 1.1. Results from the deepest trough (Ajdabiya), Etel (Gas pron in Whadyat trough), Kalash, and Hagfa constitute F organofacies, mainly. The Rachmat and Sirt shale both have D/E to B organofacies with % TOC > 1.2, thus indicating the best organofacies quality in Ajdabiya trough. In Maragh trough, results show that Etel F organofacies and D/E, C to B organofacies related to Middle Nubian, Rachmat, and Sirte shale have %TOC > 0.66. Towards the eastern Sirt basin, in troughs (Hameimat, Faregh, and Sarir), results show that the Middle Nubian, Etel, Rachmat, and Sirte shales are strongly dominated by D/E, C to B (% TOC > 0.75) organofacies.

Keywords: Etel, Mid-Nubian, organic facies, Rachmat, Sirt basin, Sirte shale

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Authors: Vineet Barwal, Sajid Husain, Nanhe Kumar Gupta, Soumyarup Hait, Sujeet Chaudhary

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High perpendicular magnetic anisotropy (PMA) and low damping constant (α) in ferromagnets are one of the few necessary requirements for their potential applications in the field of spintronics. In this regards, ferromagnetic τ-phase of MnAl possesses the highest PMA (Ku > 107 erg/cc) at room temperature, high saturation magnetization (Ms~800 emu/cc) and a Curie temperature of ~395K. In this work, we have investigated the magnetotransport behaviour of this potentially useful binary system MnₓAl₁₋ₓ films were synthesized by co-sputtering (pulsed DC magnetron sputtering) on Si/SiO₂ (where SiO₂ is native oxide layer) substrate using 99.99% pure Mn and Al sputtering targets. Films of constant thickness (~25 nm) were deposited at the different growth temperature (Tₛ) viz. 30, 300, 400, 500, and 600 ºC with a deposition rate of ~5 nm/min. Prior to deposition, the chamber was pumped down to a base pressure of 2×10⁻⁷ Torr. During sputtering, the chamber was maintained at a pressure of 3.5×10⁻³ Torr with the 55 sccm Ar flow rate. Films were not capped for the purpose of electronic transport measurement, which leaves a possibility of metal oxide formation on the surface of MnAl (both Mn and Al have an affinity towards oxide formation). In-plane and out-of-plane transverse magnetoresistance (MR) measurements on films sputtered under optimized growth conditions revealed non-saturating behavior with MR values ~6% and 40% at 9T, respectively at 275 K. Resistivity shows a parabolic dependence on the field H, when the H is weak. At higher H, non-saturating positive MR that increases exponentially with the strength of magnetic field is observed, a typical character of hopping type conduction mechanism. An anomalous decrease in MR is observed on lowering the temperature. From the temperature dependence of reistivity, it is inferred that the two competing states are metallic and semiconducting, respectively and the energy scale of the phenomenon produces the most interesting effects, i.e., the metal-insulator transition and hence the maximum sensitivity to external fields, at room temperature. Theory of disordered 3D systems effectively explains the crossover temperature coefficient of resistivity from positive to negative with lowering of temperature. These preliminary findings on the MR behavior of MnAl thin films will be presented in detail. The anomalous large MR in mixed phase MnAl system is evidently useful for future spintronic applications.

Keywords: magnetoresistance, perpendicular magnetic anisotropy, spintronics, thin films

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Authors: Ji Hun Choi, Seung Un Chae, Kyeong Suk Cho

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Synthetic resins are widely used in various fields including electricity, engineering, construction and agriculture. Many of interior and exterior finishing materials for buildings are synthetic resin products. In this study, full-scale fire tests were conducted on polyvinyl chloride, polypropylene and urethane in accordance with the “ISO 9705: Fire test - Full-scale room test for surface products” to measure heat release rate, toxic gas emission and smoke production rate. Based on the tests, fire growth pattern and fire risk were analyzed. Findings from the tests conducted on polyvinyl chloride and urethane are as follows. The total heat release rate and total smoke production rate of polyvinyl chloride were 98.89MW and 5284.41m2, respectively and its highest CO2 concentration was 0.149%. The values obtained from the test with urethane were 469.94 MW, 3396.28 m2 and 1.549%. While heat release rate and CO2 concentration were higher in urethane implying its high combustibility, smoke production rate was 1.5 times higher in polyvinyl chloride. Follow-up tests are planned to be conducted to accumulate data for the evaluation of heat emission and fire risk associated with synthetic resins.

Keywords: synthetic resins, fire test, full-scale test, heat release rate, smoke production rate, polyvinyl chloride, polypropylene, urethane

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Authors: P.P. Rupasinghe, A.H. Farid

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The Aleutian mink disease virus (AMDV, Carnivore amdoparvovirus 1) causes persistent infection, plasmacytosis, and formation and deposition of immune complexes in various organs in adult mink, leading to glomerulonephritis, arteritis and sometimes death. The disease has no cure nor an effective vaccine, and identification and culling of mink positive for anti-AMDV antibodies have not been successful in controlling the infection in many countries. The failure to eradicate the virus from infected farms may be caused by keeping false-negative individuals on the farm, virus transmission from wild animals, or neighboring farms. The identification of sources of infection, which can be performed by comparing viral sequences, is important in the success of viral eradication programs. High mutation rates could cause inaccuracies when viral sequences are used to trace back an infection to its origin. There is no published information on the mutation rate of AMDV either in vivo or in vitro. The in vivo estimation is the most accurate method, but it is difficult to perform because of the inherent technical complexities, namely infecting live animals, the unknown numbers of viral generations (i.e., infection cycles), the removal of deleterious mutations over time and genetic drift. The objective of this study was to determine the mutation rate of AMDV on which no information was available. A homogenate was prepared from the spleen of one naturally infected American mink (Neovison vison) from Nova Scotia, Canada (parental template). The near full-length genome of this isolate (91.6%, 4,143 bp) was bidirectionally sequenced. A group of black mink was inoculated with this homogenate (descendant mink). Spleen sampled were collected from 10 descendant mink after 16 weeks post-inoculation (wpi) and from anther 10 mink after 176 wpi, and their near-full length genomes were bi-directionally sequenced. Sequences of these mink were compared with each other and with the sequence of the parental template. The number of nucleotide substitutions at 176 wpi was 3.1 times greater than that at 16 wpi (113 vs 36) whereas the estimates of mutation rate at 176 wpi was 3.1 times lower than that at 176 wpi (2.85×10-3 vs 9.13×10-4 substitutions/ site/ year), showing a decreasing trend in the mutation rate per unit of time. Although there is no report on in vivo estimate of the mutation rate of DNA viruses in animals using the same method which was used in the current study, these estimates are at the higher range of reported values for DNA viruses determined by various techniques. These high estimates are logical based on the wide range of diversity and pathogenicity of AMDV isolates. The results suggest that increases in the number of nucleotide substitutions over time and subsequent divergence make it difficult to accurately trace back AMDV isolates to their origin when several years elapsed between the two samplings.

Keywords: Aleutian mink disease virus, American mink, mutation rate, nucleotide substitution

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Authors: Calvin Chiu, Samar Saade Needham

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The factors associated with the development of major depressive disorder (MDD) have been an ongoing area of concern within the field of psychopathology. Among parents, the rise in stress factors for individuals receiving less social support contributes to an increase in MDD cases. Understanding the causal aspects of MDD through the interworking of stress development within social support disparities provides critical insights into preventive measures for depressive symptoms. The present study seeks to assess the impact of social support on stress formation within MDD. Such that single parents lacking social support prompt an increase in stress formation, which proliferates the progression of MDD. Participants in this study were 450 ethnic minority mothers and fathers experiencing health inequities during pregnancy and early childhood. Perceived stress, social support, and depression are assessed by multi-item questionnaires that produce score ranges for general findings. Results indicated that lower social support scores resulted in higher depression scores, and higher perceived stress scores produced higher depression scores. Furthermore, single parents reported higher depression scores. These findings overlap with studies on paternal depression and suggest that MDD is a product of stress accumulation due to declining social support systems. Future studies may specify effective social support systems for decreasing stress accumulation in MDD formation in preventive strategies.

Keywords: major depressive disorder, stress formation, cognitive-behavioral outcomes, deficit-based behaviors

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Authors: C. Bunsanit

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This paper presents the refinement method for two beams formation of wideband smart antenna. The refinement method for weighting coefficients is based on Fully Spatial Signal Processing by taking Inverse Discrete Fourier Transform (IDFT), and its simulation results are presented using MATLAB. The radiation pattern is created by multiplying the incoming signal with real weights and then summing them together. These real weighting coefficients are computed by IDFT method; however, the range of weight values is relatively wide. Therefore, for reducing this range, the refinement method is used. The radiation pattern concerns with five input parameters to control. These parameters are maximum weighting coefficient, wideband signal, direction of mainbeam, beamwidth, and maximum of minor lobe level. Comparison of the obtained simulation results between using refinement method and taking only IDFT shows that the refinement method works well for wideband two beams formation.

Keywords: fully spatial signal processing, beam forming, refinement method, smart antenna, weighting coefficient, wideband

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Authors: Suminar Pratapa, Agus Riyanto, Silmi Machmudah, Sri Yani Purwaningsih

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The objective of this study was to investigate the optical properties of polyvinyl alcohol (PVA) and its prospective applications by adding crystalline silica which is usually used as a reinforcing agent. To do this, we synthesized and evaluated PVA-based composites reinforced with silica crystals, namely cristobalite, derived from rice husk. The experimental procedure involved the production of SiO2 particles using rice husk precursors, which were subsequently subjected to calcination at a rate of 10 °C/min for a duration of 3 hours. This process primarily resulted in the formation of SiO2 crystals in the cristobalite phase, according to X-ray diffraction (XRD). Following this, the crystals were incorporated into polyvinyl alcohol (PVA) via a casting technique, resulting in the formation of composite sheets. The SiO2 contents in the composites were 0, 2.5, 5.0, and 10.%. XRD and Fourier-transform infrared spectroscopy (FTIR) techniques provided confirmation of the composites' successful synthesis, i.e., it did not yield any indications of chemical bonding between polyvinyl alcohol (PVA) and silicon dioxide (SiO2), indicating that the interaction was limited to interfacial reactions. The incorporation of SiO2 crystals resulted in a notable enhancement in UV-vis light absorption and a decrease in the optical band gap. Addition of 2.5, 5.0, and 10.% SiO2, for example, decreases the direct optical band gap of the composites form 5.37, 5.19, and 5.02 eV respectively, while the indirect band gaps of the samples were 4.44, 4.84, and 4.48 eV, correspondingly. These findings emphasize the efficacy of rice husk-derived SiO2 crystals as both reinforcement agents and modifiers of optical properties in the polymer composites, showcasing their significant potential to modify the composite's structural and optical characteristics.

Keywords: rice husk, cristaline SiO₂, PVA-based composites, structural characteristics, optical properties.

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Authors: M Jeffri Arlinandes Chandra, Puwaningdyah Murti Wahyuni, Dewi Mutiara M Jeffri Arlinandes Chandra, Puwaningdyah Murti Wahyuni, Dewi Mutiara

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Indonesia is a state of the law in accordance with article 1 paragraph 3 of the Constitution of the Republic of Indonesia (1945 Constitution), namely, 'the State of Indonesia is a state of law'. The consequences of the rule of law are making the law as the main commanding officer or making the law as a basis for carrying out an action taken by the state. The types of regulations and procedures for the formation of legislation in Indonesia are contained in Law Number 12 of 2011 concerning the Formation of Legislation. Various attempts were made to make quality regulations both in the formal hierarchy and material hierarchy such as synchronization and harmonization in the formation of laws and regulations so that there is no conflict between equal and hierarchical laws, but the fact is that there are still many conflicting regulations found between one another. This can be seen clearly in the many laws and regulations that were sued to judicial institutions such as the Constitutional Court (MK) and the Supreme Court (MA). Therefore, it is necessary to have a formulation regarding the governance of the formation of laws and regulations so as to minimize the occurrence of lawsuits to the court so that positive law can be realized which can be used today and for the future (ius constituendum). The research method that will be used in this research is a combination of normative research (library research) supported by empirical data from field research so that it can formulate concepts and answer the challenges being faced. First, the structuring of laws and regulations in Indonesia must start from the inventory of laws and regulations, whether they can be classified based on the type of legislation, what are they set about, the year of manufacture, etc. so that they can be clearly traced to the regulations relating to the formation of laws and regulations. Second, the search and revocation/revocation of laws and regulations that do not exist in the state registration system. Third, the periodic evaluation system is carried out at every level of the hierarchy of laws and regulations. These steps will form an ideal model of laws and regulations in Indonesia both in terms of content and material so that the instructions can be codified and clearly inventoried so that they can be accessed by the wider community as a concrete manifestation of the principle that all people know the law (presumptio iures de iure).

Keywords: legislation, review, evaluation, reconstruction

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Authors: Andrey Cherdantsev, Mikhail Cherdantsev, Sergey Isaenkov, Dmitriy Markovich

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In annular gas-liquid flow, liquid flows as a film along pipe walls sheared by high-velocity gas stream. Film surface is covered by large-scale disturbance waves which affect pressure drop and heat transfer in the system and are necessary for entrainment of liquid droplets from film surface into the core of gas stream. Disturbance waves are a highly complex and their properties are affected by numerous parameters. One of such aspects is flow development, i.e., change of flow properties with the distance from the inlet. In the present work, this question is studied using brightness-based laser-induced fluorescence (BBLIF) technique. This method enables one to perform simultaneous measurements of local film thickness in large number of points with high sampling frequency. In the present experiments first 50 cm of upward and downward annular flow in a vertical pipe of 11.7 mm i.d. is studied with temporal resolution of 10 kHz and spatial resolution of 0.5 mm. Thus, spatiotemporal evolution of film surface can be investigated, including scenarios of formation, acceleration and coalescence of disturbance waves. The behaviour of disturbance waves' velocity depending on phases flow rates and downstream distance was investigated. Besides measuring the waves properties, the goal of the work was to investigate the interrelation between disturbance waves properties and integral characteristics of the flow such as interfacial shear stress and flow rate of dispersed phase. In particular, it was shown that the initial acceleration of disturbance waves, defined by the value of shear stress, linearly decays with downstream distance. This lack of acceleration which may even lead to deceleration is related to liquid entrainment. Flow rate of disperse phase linearly grows with downstream distance. During entrainment events, liquid is extracted directly from disturbance waves, reducing their mass, area of interaction to the gas shear and, hence, velocity. Passing frequency of disturbance waves at each downstream position was measured automatically with a new algorithm of identification of characteristic lines of individual disturbance waves. Scenarios of coalescence of individual disturbance waves were identified. Transition from initial high-frequency Kelvin-Helmholtz waves appearing at the inlet to highly nonlinear disturbance waves with lower frequency was studied near the inlet using 3D realisation of BBLIF method in the same cylindrical channel and in a rectangular duct with cross-section of 5 mm by 50 mm. It was shown that the initial waves are generally two-dimensional but are promptly broken into localised three-dimensional wavelets. Coalescence of these wavelets leads to formation of quasi two-dimensional disturbance waves. Using cross-correlation analysis, loss and restoration of two-dimensionality of film surface with downstream distance were studied quantitatively. It was shown that all the processes occur closer to the inlet at higher gas velocities.

Keywords: annular flow, disturbance waves, entrainment, flow development

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Authors: Smita Mondal, Dinesh Kumar Pandey, Prakash Biswas

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During past two decades, considerable attention has been given to the value addition of biodiesel derived glycerol (~10wt.%) to make the biodiesel industry economically viable. Among the various glycerol value-addition methods, hydrogenolysis of glycerol to 1,2-propanediol is one of the attractive and promising routes. In this study, highly active and selective γ-Al₂O₃ supported bimetallic Cu-Ni catalyst was developed for selective hydrogenolysis of glycerol to 1,2-propanediol in the liquid phase. The catalytic performance was evaluated in a high-pressure autoclave reactor. The formation of mixed oxide indicated the strong interaction of Cu, Ni with the alumina support. Experimental results demonstrated that bimetallic copper-nickel catalyst was more active and selective to 1,2-PDO as compared to monometallic catalysts due to bifunctional behavior. To verify the effect of calcination temperature on the formation of Cu-Ni mixed oxide phase, the calcination temperature of 20wt.% Cu:Ni(1:1)/Al₂O₃ catalyst was varied from 300°C-550°C. The physicochemical properties of the catalysts were characterized by various techniques such as specific surface area (BET), X-ray diffraction study (XRD), temperature programmed reduction (TPR), and temperature programmed desorption (TPD). The BET surface area and pore volume of the catalysts were in the range of 71-78 m²g⁻¹, and 0.12-0.15 cm³g⁻¹, respectively. The peaks at the 2θ range of 43.3°-45.5° and 50.4°-52°, was corresponded to the copper-nickel mixed oxidephase [JCPDS: 78-1602]. The formation of mixed oxide indicated the strong interaction of Cu, Ni with the alumina support. The crystallite size decreased with increasing the calcination temperature up to 450°C. Further, the crystallite size was increased due to agglomeration. Smaller crystallite size of 16.5 nm was obtained for the catalyst calcined at 400°C. Total acidic sites of the catalysts were determined by NH₃-TPD, and the maximum total acidic of 0.609 mmol NH₃ gcat⁻¹ was obtained over the catalyst calcined at 400°C. TPR data suggested the maximum of 75% degree of reduction of catalyst calcined at 400°C among all others. Further, 20wt.%Cu:Ni(1:1)/γ-Al₂O₃ catalyst calcined at 400°C exhibited highest catalytic activity ( > 70%) and 1,2-PDO selectivity ( > 85%) at mild reaction condition due to highest acidity, highest degree of reduction, smallest crystallite size. Further, the modified Power law kinetic model was developed to understand the true kinetic behaviour of hydrogenolysis of glycerol over 20wt.%Cu:Ni(1:1)/γ-Al₂O₃ catalyst. Rate equations obtained from the model was solved by ode23 using MATLAB coupled with Genetic Algorithm. Results demonstrated that the model predicted data were very well fitted with the experimental data. The activation energy of the formation of 1,2-PDO was found to be 45 kJ mol⁻¹.

Keywords: glycerol, 1, 2-PDO, calcination, kinetic

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Authors: Fahad A. Alotaibi

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An increase in salt dissolution rate with continuous water flow is expected to lead to the progressive collapse of the soil structure. Evaluation of the relationship between soil salt dissolution and the variation of sabkha soil permeability in terms of type, rate, and quantity in order to assure construction safety in these environments. The current study investigates the relationship of soil permeability with the rate of dissolution of calcium (Ca2+), sulfate (SO4-2), chloride (CL−1), magnesium (Mg2+), sodium (Na+), and potassium (K+1) ions. Results revealed an increase in sabkha soil permeability with the rate of ions dissolution. This makes the efficiency of using a waterproofing stabilization agent in the reduction of sabkha salts dissolution the main criterion is selecting suitable stabilizing method.

Keywords: sabkha, permeability, salts, dissolution

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Authors: Lule Basha, Eralda Gjika

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The exchange rate is one of the most important economic variables, especially for a small, open economy such as Albania. Its effect is noticeable in one country's competitiveness, trade and current account, inflation, wages, domestic economic activity, and bank stability. This study investigates the fluctuation of Albania’s exchange rates using monthly average foreign currency, Euro (Eur) to Albanian Lek (ALL) exchange rate with a time span from January 2008 to June 2021, and the macroeconomic factors that have a significant effect on the exchange rate. Initially, the Random Forest Regression algorithm is constructed to understand the impact of economic variables on the behavior of monthly average foreign currencies exchange rates. Then the forecast of macro-economic indicators for 12 months was performed using time series models. The predicted values received are placed in the random forest model in order to obtain the average monthly forecast of the Euro to Albanian Lek (ALL) exchange rate for the period July 2021 to June 2022.

Keywords: exchange rate, random forest, time series, machine learning, prediction

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Authors: Abdulmagid A. Khattabi, Ahmed A. Hablus, Osama Ab. M. Shafah

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The goal of this work is to understand how the thermal influence of combustion chamber deposits can be utilized to expand the operating range of HCCI combustion. In order to do this, two main objectives must first be met; tracking deposit formation trends in an HCCI engine and determining the sensitivity of HCCI combustion to CCD. This requires testing that demonstrates the differences in combustion between a clean engine and one with deposits coating the chamber. This will involve a long-term test that tracks the effects of CCD on combustion. The test will start with a clean engine. One baseline HCCI operating point is maintained for the duration of the test during which gradual combustion chamber deposit formation will occur. Combustion parameters, including heat release rates and emissions will be tracked for the duration and compared to the case of a clean engine. This work will begin by detailing the specifics of the test procedure and measurements taken throughout the test. Then a review of the effects of the gradual formation of deposits in the engine will be given.

Keywords: fuels, fuel atomization, pattern factor, alternate fuels combustion, efficiency gas turbine combustion, lean blow out, exhaust and liner wall temperature

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Authors: Tareq Nikzad

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Since the first bank was established in 1933, Afghanistan's banking sector has seen a number of variations but hasn't been able to grow to its full potential because of the civil war. The implementation of dual banks in Afghanistan is investigated in this study in relation to the effects of inflation and interest rates. This research took data from World Bank Data (WBD) over a period of nineteen years. For the banking sector, inflation, which is the general rise in prices of goods and services over time, presents considerable difficulties. The objectives of this research are to analyze the effect of inflation and interest rates on conventional and Islamic banks in Afghanistan, identify potential differences between these two banking models, and provide insights for policymakers and practitioners. A mixed-methods approach is used in the research to analyze quantitative data and qualitatively examine the unique difficulties that banks in Afghanistan's economic atmosphere encounter. The findings contribute to the understanding of the relationship between interest rate, inflation rate, and the performance of both banking systems in Afghanistan. The paper concludes with recommendations for policymakers and banking institutions to enhance the stability and growth of the banking sector in Afghanistan. Interest is described as "a prefixed rate for use or borrowing of money" from an Islamic perspective. This "prefixed rate," known in Islamic economics as "riba," has been described as "something undesirable." Furthermore, by using the time series regression data technique on the annual data from 2003 to 2021, this research examines the effect of CPI inflation rate and interest rate of Banking in Afghanistan.

Keywords: inflation, Islamic banking, conventional banking, interest, Afghanistan, impact

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Authors: Victor S. Klimin, Alexey A. Rezvan, Maxim S. Solodovnik, Oleg A. Ageev

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In this paper, the problems of existing methods of profiling and surface modification of nanoscale arsenide-gallium structures are analyzed. The use of a combination of methods of local anodic oxidation and plasma chemical etching to solve this problem is considered. The main features that make this technology one of the promising areas of modification and profiling of near-surface layers of solids are demonstrated. In this paper, we studied the effect of formation stress and etching time on the geometrical parameters of the etched layer and the roughness of the etched surface. Experimental dependences of the thickness of the etched layer on the time and stress of formation were obtained. The surface analysis was carried out using atomic force microscopy methods, the corresponding profilograms were constructed from the obtained images, and the roughness of the etched surface was studied accordingly. It was shown that at high formation voltage, the depth of the etched surface increased, this is due to an increase in the number of active particles (oxygen ions and hydroxyl groups) formed as a result of the decomposition of water molecules in an electric field, during the formation of oxide nanostructures on the surface of gallium arsenide. Oxide layers were used as negative masks for subsequent plasma chemical etching by the STE ICPe68 unit. BCl₃ was chosen as the chlorine-containing gas, which differs from analogs in some parameters for the effect of etching of nanostructures based on gallium arsenide in the low-temperature plasma. The gas mixture of reaction chamber consisted of a buffer gas NAr = 100 cm³/min and a chlorine-containing gas NBCl₃ = 15 cm³/min at a pressure P = 2 Pa. The influence of these methods modes, which are formation voltage and etching time, on the roughness and geometric parameters, and corresponding dependences are demonstrated. Probe nanotechnology was used for surface analysis.

Keywords: nanostructures, GaAs, plasma chemical etching, modification structures

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Authors: Caroline M. B. De Araujo, Helenise A. Do Nascimento, Claudia J. Da S. Cavalcanti, Mauricio A. Da Motta Sobrinho, Maria F. Pimentel

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Oil production is often followed by the joint production of water and gas. During the journey up to the surface, due to severe conditions of temperature and pressure, the mixing between these three components normally occurs. Thus, the three phases separation process must be one of the first steps to be performed after crude oil extraction, where the water-oil separation is the most complex and important step, since the presence of water into the process line can increase corrosion and hydrates formation. A wide range of methods can be applied in order to proceed with oil-water separation, being more commonly used: flotation, hydrocyclones, as well as the three phase separator vessels. Facing what has been presented so far, it is the aim of this paper to study a system consisting of a three-phase separator, evaluating the influence of three variables: temperature, working pressure and separator type, for two types of oil (light and heavy), by performing two factorial design plans 23, in order to find the best operating condition. In this case, the purpose is to obtain the greatest oil flow rate in the product stream (m3/h) as well as the lowest percentage of water in the oil stream. The simulation of the three-phase separator was performed using Aspen Hysys®2006 simulation software in stationary mode, and the evaluation of the factorial experimental designs was performed using the software Statistica®. From the general analysis of the four normal probability plots of effects obtained, it was observed that interaction effects of two and three factors did not show statistical significance at 95% confidence, since all the values were very close to zero. Similarly, the main effect "separator type" did not show significant statistical influence in any situation. As in this case, it has been assumed that the volumetric flow of water, oil and gas were equal in the inlet stream, the effect separator type, in fact, may not be significant for the proposed system. Nevertheless, the main effect “temperature” was significant for both responses (oil flow rate and mass fraction of water in the oil stream), considering both light and heavy oil, so that the best operation condition occurs with the temperature at its lowest level (30oC), since the higher the temperature, the liquid oil components pass into the vapor phase, going to the gas stream. Furthermore, the higher the temperature, the higher the formation water vapor, so that ends up going into the lighter stream (oil stream), making the separation process more difficult. Regarding the “working pressure”, this effect showed to be significant only for the oil flow rate, so that the best operation condition occurs with the pressure at its highest level (9bar), since a higher operating pressure, in this case, indicated a lower pressure drop inside the vessel, generating lower level of turbulence inside the separator. In conclusion, the best-operating condition obtained for the proposed system, at the studied range, occurs for temperature is at its lowest level and the working pressure is at its highest level.

Keywords: factorial experimental design, oil production, simulation, three-phase separator

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Authors: Martins Gbenga., Orosun M. M., Olowookere C. J., Bamidele Lateef

Abstract:

Radiation exposures from diagnostic medical examinations are almost always justified by the benefits of accurate diagnosis of possible disease conditions. The aim is to assess the influence of selected exposure parameters on scattered dose rates. The research was carried out using Gamma Scout software installation on the Computer system (Laptop) to record the radiation counts, pulse rate, and dose rate for 136 patients. Seventy-three patients participated in the male category with 53.7%, while 63 females participated with 46.3%. The mean and standard deviation value for each parameter is recorded, and tube potential is within 69.50±11.75 ranges between 52.00 and 100.00, tube current is within 23.20±17.55 ranges between 4.00 and 100.00, focus skin distance is within 73.195±33.99 and ranges between 52.00 and 100.00. Dose Rate (DRate in µSv/hr) is significant at an interval of 0.582 and 0.587 for tube potential and body thickness (cm). Tube potential is significant at an interval of 0.582 and 0.842 of DRate (µSv/hr) and body thickness (cm). The study was compared with other studies. The exposure parameters selected during each examination contributed to scattered radiation. A quality assurance program (QAP) is advised for the center.

Keywords: x-radiation, exposure rate, dose rate, tube potentials, scattered radiation, diagnostic examination

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Authors: N. G. Margiani, I. G. Kvartskhava, G. A. Mumladze, Z. A. Adamia

Abstract:

Chemical doping with different elements and compounds at various amounts represents the most suitable approach to improve the superconducting properties of bismuth-based superconductors for technological applications. In this paper, the influence of partial substitution of Sr(BO₂)₂ for SrO on the phase formation kinetics and transport properties of (Bi,Pb)-2223 HTS has been studied for the first time. Samples with nominal composition Bi_1.7Pb_0.3Sr_2-xCa₂Cu₃O_y[Sr(BO₂)₂]_x, x=0, 0.0375, 0.075, 0.15, 0.25, were prepared by the standard solid state processing. The appropriate mixtures were calcined at 845 ^oC for 40 h. The resulting materials were pressed into pellets and annealed at 837 ^oC for 30 h in air. Superconducting properties of undoped (reference) and Sr(BO₂)₂-doped (Bi,Pb)-2223 compounds were investigated through X-ray diffraction (XRD), resistivity (ρ) and transport critical current density (J_c) measurements. The surface morphology changes in the prepared samples were examined by scanning electron microscope (SEM). XRD and J_c studies have shown that the low level Sr(BO₂)₂ doping (x=0.0375-0.075) to the Sr-site promotes the formation of high-T_c phase and leads to the enhancement of current carrying capacity in (Bi,Pb)-2223 HTS. The doped sample with x=0.0375 has the best performance compared to other prepared samples. The estimated volume fraction of (Bi,Pb)-2223 phase increases from ~25 % for reference specimen to ~70 % for x=0.0375. Moreover, strong increase in the self-field J_c value was observed for this dopant amount (J_c=340 A/cm²), compared to an undoped sample (J_c=110 A/cm²). Pronounced enhancement of superconducting properties of (Bi,Pb)-2223 superconductor can be attributed to the acceleration of high-T_c phase formation as well as the improvement of inter-grain connectivity by small amounts of Sr(BO₂)₂ dopant.

Keywords: bismuth-based superconductor, critical current density, phase formation, Sr(BO₂)₂ doping

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Authors: Sepdiana W. Rahmawati, Santi A. P. Anggraini

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The world of education has made progress with the various new technologies with help of computer. No exception physics education, especially virtual physics practical work. By doing practical work, memory of physics concept will be more advantageous for student and they will understand the essence of actual physics, not only spiked formula. With help of computers, created a variety of applications that can be used by students to perform virtual practical work and students will start thinking systematically to be able find its own concepts and understand the application of physics.

Keywords: essence of physics, formation concept, physics concept, virtual practical work

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Authors: Nacira Mecheri, N. Boussid

Abstract:

A new chemical mechanism designed to study the process of forming the first aromatic ring (benzene) and polycyclic aromatic hydrocarbons (PAH) from a flame of acetylene (C2H2) has been developed. The mechanism developed, contains 50 chemical species involved in 268 reversible elementary reactions. The comparison between the results from modelling and experimental measurements allowed us to test the validity of the postulated mechanism in specific experimental conditions. Kinetic analysis of the flame by calculating the maximum rates for each elementary reaction, allowed us to identify key reactions pathways of consumption and formation of main precursors of soot.

Keywords: benzene, PAH, acetylene, modeling, flame, soot

Procedia PDF Downloads 317

Authors: Riaz Ahmad, Jiazhong Zhang, Asma Farooqi

Abstract:

In this study, mass transport between separation bubbles and the flow around a two-dimensional airfoil are numerically investigated using Lagrangian Coherent Structures (LCSs). Finite Time Lyapunov Exponent (FTLE) technique is used for the computation to identify invariant manifolds and LCSs. Moreover, the Characteristic Base Split (CBS) scheme combined with dual time stepping technique is applied to simulate such transient flow at low Reynolds number. We then investigate the evolution of vortex structures during the transport process with the aid of LCSs. To explore the vortex formation at the surface of the airfoil, the dynamics of separatrix is also taken into account which is formed by the combination of stable-unstable manifolds. The Lagrangian analysis gives a detailed understanding of vortex dynamics and separation bubbles which plays a significant role to explore the performance of the unsteady flow generated by the airfoil. Transport process and flow separation phenomena are studied extensively to analyze the flow pattern by Lagrangian point of view.

Keywords: transport phenomena, CBS Method, vortex formation, Lagrangian Coherent Structures

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Authors: Jian-Xiu Wan, Yao Yin

Abstract:

In complex terrain and poor geological conditions areas, Railway, highway and other transportation constructions are still strongly developing. However, various geological disasters happened such as landslide, rock heap and so on. According to the results of geological investigation, the form of skirt (trapezoidal), semicircle and triangle rock heaps are mainly due to complex internal force and external force, in a certain extent, which is related to the terrain, the nature of the rock mass, the supply area and the surface shape of rock heap. Combined with the above factors, discrete element numerical simulation of rock mass is established under different terrain conditions based on 3DEC, and accelerated formation process of rock heap under seismic action is simulated. The fragmentation structure supply area is calculated, in which the most dangerous area is located. At the same time, the formation mechanism and development process are studied in different terrain conditions, and the structure of rock heap is judged by section, which can provide a strong theoretical and technical support for the prevention and control of geological disasters.

Keywords: 3DEC, fragmentation structure, rock heap, slope, seismic action

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Authors: Ali Abd El-Aty, Ahmed Tauseef, Ahmad Farooq

Abstract:

This research aims at analyzing and optimizing the hydroforming process parameters to achieve a sound bulged tube without failure. Theoretical constitutive model is formulated to develop a working diagram including process window, which represents the optimize region to carry out the hydroforming process and predict the type of tube failure during the process accurately. The model is applied into different bulging ratios for low carbon steel (C1010). From this study, it is concluded that the tubes with bulging ratios up to 50% and 70% are successfully formed without defects. The tubes with bulging ratio of 90% are successfully formed by hydroforming with optimized the loading path (axial feed versus internal pressure) within the process window. The working diagram is modified due to different types of formation of wrinkling during the hydroforming process. The formation of wrinkles with increasing axial feed can be useful in terms of the achievement of higher bulging ratio and/or less thinning and this type of wrinkles can be overcome through the internal pressure in the later stage of the hydroforming process. On the other hand, the formation of wrinkles may be harmful, if it cannot be reversed.

Keywords: finite element, hydroforming, process window, wrinkling

Procedia PDF Downloads 257

Authors: Pavel Zlabek, Vaclav Mentl

Abstract:

The fatigue crack growth rate evaluation is a basic experimental characteristic when assessment o f the remaining lifetime is needed. Within the repair welding technology project, the crack growth rate at cyclic loading was measured in base and weld metals and in the situation when cracks were initiated in base metal and grew into the weld metal through heat-affected zone and back to the base metal. Two welding technologies were applied and specimens in as-welded state and after heat treatment were tested. Fatigue crack growth rate measurement was performed on CrMoV pressure vessel steel and the tests were performed at room temperature. The crack growth rate was measured on CCT test specimens (see figure) for both the base and weld metals and also in the case of crack subsequent transition through all the weld zones. A 500 kN MTS controlled electro-hydraulic testing machine and Model 632.13C-20 MTS extensometer were used to perform the tests.

Keywords: cracks, fatigue, steels, weldments

Procedia PDF Downloads 500

Authors: Foluke E. Sola-Ojo, Ibraheem A. Abubakar, Semiu F. Bello, Isiaka H. Fatima, Sule Bisola, Adesina M. Olusegun, Adeniyi C. Adeola

Abstract:

The domesticated pigeon, Columba livia domestica, has many valuable characteristics, including high nutritional value and fast growth rate. There is a lack of information on its genetic diversity in Nigeria; thus, the genetic variability in mitochondrial cytochrome oxidase subunit I (COI) sequences of 150 domestic pigeons from four different locations was examined. Three haplotypes (HT) were identified in Nigerian populations; the most common haplotype, HT1, was shared with wild and domestic pigeons from Europe, America, and Asia, while HT2 and HT3 were unique to Nigeria. The overall haplotype diversity was 0.052± 0.025, and nucleotide diversity was 0.026± 0.068 across the four investigated populations. The phylogenetic tree showed significant clustering and genetic relationship of Nigerian domestic pigeons with other global pigeons. The median-joining network showed a star-like pattern suggesting population expansion. AMOVA results indicated that genetic variations in Nigerian pigeons mainly occurred within populations (99.93%), while the Neutrality tests results suggested that the Nigerian domestic pigeons’ population experienced recent expansion. This study showed a low genetic diversity and population differentiation among Nigerian domestic pigeons consistent with a relatively conservative COI sequence with few polymorphic sites. Furthermore, the COI gene could serve as a candidate molecular marker to investigate the genetic diversity and origin of pigeon species. The current data is insufficient for further conclusions; therefore, more research evidence from multiple molecular markers is required.

Keywords: Nigeria pigeon, COI, genetic diversity, genetic variation, conservation

Procedia PDF Downloads 151

Authors: Caje F. Pinto, Jivan S. Parab, Gourish M. Naik

Abstract:

This paper is about the development of non-invasive heart rate and oxygen saturation in human blood using Altera NIOS II soft-core processor system. In today's world, monitoring oxygen saturation and heart rate is very important in hospitals to keep track of low oxygen levels in blood. We have designed an Embedded System On Peripheral Chip (SOPC) reconfigurable system by interfacing two LED’s of different wavelengths (660 nm/940 nm) with a single photo-detector to measure the absorptions of hemoglobin species at different wavelengths. The implementation of the interface with Finger Probe and Liquid Crystal Display (LCD) was carried out using NIOS II soft-core system running on Altera NANO DE0 board having target as Cyclone IVE. This designed system is used to monitor oxygen saturation in blood and heart rate for different test subjects. The designed NIOS II processor based non-invasive heart rate and oxygen saturation was verified with another Operon Pulse oximeter for 50 measurements on 10 different subjects. It was found that the readings taken were very close to the Operon Pulse oximeter.

Keywords: heart rate, NIOS II, oxygen saturation, photoplethysmography, soft-core, SOPC

Procedia PDF Downloads 171