Search results for: high temperature corrosion

Authors: Gulshan Kumar Jawa, Sandeep Mohan Ahuja

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With the increase in industrialization, the presence of heavy metals in wastewater streams has turned into a serious concern for the ecosystem. The metals diffuse through the food chains, causing various health hazards. Conventional methods used to remove these heavy metals from water have some limitations, such as cost, secondary pollution due to sludge formation, recovery of metal, economic viability at low metal concentrations, etc. Many of the biomaterials have been investigated by researchers for the adsorption of heavy metals from water solutions as an alternative technique for the last two decades and have found promising results. In this paper, the batch study on the use of pods of acacia karoo for the adsorption of Cd(II) and Pb(II) from aqueous solutions has been reported. The effect of various parameters on the removal of metal ions, such as pH, contact time, stirring speed, initial metal ion concentration, adsorbent dose, and temperature, have been established to find the optimum parameters through one parameter optimization. Further, kinetic, equilibrium, and thermodynamic studies have been conducted. The pods of acacia karoo have shown great potential for adsorption of Cd(II) and Pb(II) from aqueous solutions and have proven to be a better and more economical alternative for the purpose.

Keywords: adsorption, heavy metals, biomaterials, Cadmium(II), Lead(II), pods of acacia karoo

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Authors: Avinash Thakur, Parmjit S. Panesar, Manohar Singh

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The distribution coefficient, KD for the reactive extraction of lactic acid from aqueous solutions of lactic acid using 10-30% (v/v) tri-n-octyl amine (extractant) dissolved in n-hexane (inert diluent) and 20% (v/v) oleyl alcohol (modifier) was optimized by using response surface methodology (RSM). A three level Box-Behnken design was employed for experimental design, analysis of the results and to depict the combined interactive effect of seven independent variables, viz lactic acid concentration (cl), pH, TOA concentration in organic phase (ψ), treat ratio (φ), temperature (T), agitation speed (ω) and batch agitation time (τ) on distribution coefficient of lactic acid. The regression analysis recommended that the quadratic model is significant (R2 and adjusted R2 are 98.72 % and 98.69 % respectively) for analysis. A numerical optimization had resulted in maximum lactic acid distribution coefficient (KD) of 3.16 at the optimized values for test variables, cl, pH, ψ, φ, T, ω and τ as 0.15 [M], 3.0, 22.75% (v/v), 1.0 (v/v), 26°C, 145 rpm and 23 min respectively. A good agreement between the predicted and experimentally obtained values for distribution coefficient using the optimized conditions was exhibited.

Keywords: Distribution coefficient, tri-n-octylamine, lactic acid, response surface methodology

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Authors: Dib Djalel, Mordjaoui Mourad

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The current trend towards the exploitation of various renewable energy resources has become indispensable, so it is important to improve the efficiency and reliability of the GPV photovoltaic systems. Maximum Power Point Tracking (MPPT) plays an important role in photovoltaic power systems because it maximize the power output from a PV system for a given set of conditions. This paper presents a new fuzzy logic control based MPPT algorithm for solar panel. The solar panel is modeled and analyzed in Matlab/Simulink. The Solar panel can produce maximum power at a particular operating point called Maximum Power Point(MPP). To produce maximum power and to get maximum efficiency, the entire photovoltaic panel must operate at this particular point. Maximum power point of PV panel keeps on changing with changing environmental conditions such as solar irradiance and cell temperature. Thus, to extract maximum available power from a PV module, MPPT algorithms are implemented and Perturb and Observe (P&O) MPPT and fuzzy logic control FLC, MPPT are developed and compared. Simulation results show the effectiveness of the fuzzy control technique to produce a more stable power.

Keywords: MPPT, photovoltaic panel, fuzzy logic control, modeling, solar power

Procedia PDF Downloads 468

Authors: Nodar Kekelidze, David Kekelidze, Elza Khutsishvili, Bela Kvirkvelia

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The semiconductor devices are irreplaceable elements for investigations in Space (artificial Earth satellite, interplanetary space craft, probes, rockets) and for investigation of elementary particles on accelerators, for atomic power stations, nuclear reactors, robots operating on heavily radiation contaminated territories (Chernobyl, Fukushima). Unfortunately, the most important parameters of semiconductors dramatically worsen under irradiation. So creation of radiation-resistant semiconductor materials for opto and microelectronic devices is actual problem, as well as investigation of complicated processes developed in irradiated solid states. Homogeneous single crystals of InP-InAs solid solutions were grown with zone melting method. There has been studied the dependence of the optical absorption coefficient vs photon energy near fundamental absorption edge. This dependence changes dramatically with irradiation. The experiments were performed on InP, InAs and InP-InAs solid solutions before and after irradiation with electrons and fast neutrons. The investigations of optical properties were carried out on infrared spectrophotometer in temperature range of 10K-300K and 1mkm-50mkm spectral area. Radiation fluencies of fast neutrons was equal to 2·1018neutron/cm2 and electrons with 3MeV, 50MeV up to fluxes of 6·1017electron/cm2. Under irradiation, there has been revealed the exponential type of the dependence of the optical absorption coefficient vs photon energy with energy deficiency. The indicated phenomenon takes place at high and low temperatures as well at impurity different concentration and practically in all cases of irradiation by various energy electrons and fast neutrons. We have developed the common mechanism of this phenomenon for unirradiated materials and implemented the quantitative calculations of distinctive parameter; this is in a satisfactory agreement with experimental data. For the irradiated crystals picture get complicated. In the work, the corresponding analysis is carried out. It has been shown, that in the case of InP, irradiated with electrons (Ф=1·1017el/cm2), the curve of optical absorption is shifted to lower energies. This is caused by appearance of the tails of density of states in forbidden band due to local fluctuations of ionized impurity (defect) concentration. Situation is more complicated in the case of InAs and for solid solutions with composition near to InAs when besides noticeable phenomenon there takes place Burstein effect caused by increase of electrons concentration as a result of irradiation. We have shown, that in certain conditions it is possible the prevalence of Burstein effect. This causes the opposite effect: the shift of the optical absorption edge to higher energies. So in given solid solutions there take place two different opposite directed processes. By selection of solid solutions composition and doping impurity we obtained such InP-InAs, solid solution in which under radiation mutual compensation of optical absorption curves displacement occurs. Obtained result let create on the base of InP-InAs, solid solution radiation-resistant optical materials. Conclusion: It was established the nature of optical absorption near fundamental edge in semiconductor materials and it was created radiation-resistant optical material.

Keywords: InAs-InP, electrons concentration, irradiation, solid solutions

Procedia PDF Downloads 185

Authors: Samuel Opeyemi Williams, Razali Adul Hamid, Mohd Saidin Misman, Dominic Ileyemi Ajayi, Taki Eddine Seghier

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Construction industry is famous with hazardous and high-risk environment with operatives facing a greater risk of work-related fatality or injury than operatives in other industries. It is characterised with different types of accident, ranging from electrocution, trip and slip, fall from height, struck-by, explosion, trench collapse, to scaffolding accidents, with each type being caused by different factors. However, accidents are unplanned, unforeseeable and unexpected events, but regardless of the high-risk nature of the industry, accidents are preventable. The aim of the paper is to determine the extent of the utilization of the safety measures, as well as identifying the factors underlining the non-usage. A research methodology consisting of a literature review was used to identify the types and causes of site accidents, while a well-structured questionnaire was used to determine the level of the usage of safety measures on site. The data were analysed with the results revealing the use of protective clothing, safety helmet, first aid, protective shoe, safety belt, and face shield to aid safety of workers, as well as ascribing non-usage of safety measures to cost, ignorance, lack of experts and non-inclusion in contract document. Recommendations are included in the paper suggesting the enforcement of the utilization of safety measures in reducing the spate of accident occurrence on construction sites.

Keywords: construction industry, safety measures, accident, prevention

Procedia PDF Downloads 298

Authors: Ahmad Alazemi, M. Sherif El-Eskandrany, Mohamad Kishk, Thanyan AlOnaizi, Ahmad Alduweesh, Shorouq Abdullaleel

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Arc melting technique followed by top-down approach, using a high-energy ball milling technique were employed to synthesize nanocrystalline of Cu50(Zr50-xNix)50 (x = 0, 10, 20 and 30 at.%) powder particles. The end-products of the alloy powders obtained after 50 h of the ball milling time were uniform in composition and had spherical-like morphology with an average particle size of 0.75 µm in diameter. The powders, which consisted of nanocrystalline grains with an average grain size of 10 nm in diameter, were used as feedstock materials for double face coating of stainless (SUS304) sheets, using cold spraying process. The coating materials enjoyed nanocrystalline structure and uniform composition. Biofilms were grown on 20-mm2 SUS304 sheets coated coupons inoculated with 1.5 × 108 CFU ml−1 E. coli. Significant biofilm inhibition was recorded in the nanoparticles coated coupons in comparison to non-coated SUS304 coupon. In conclusion, this study demonstrates that formation of biofilms can be significantly inhibited by Cu-based alloys especially in case of high (Ni) content. The inhibition of biofilm formation by nanocrystalline powders of Cu-based provides a practical approach to achieve the inhibition of biofilms formed by an emerging pathogen.

Keywords: biofilm, Cu, E.coli, FE-HRTEM/EDS, nanomaterials, nanocrystalline

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Authors: Abdullah Işıktaş, Kevser Dincer

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The use of HEPA filters for air conditioning systems in clean rooms tends to increase progressively in pharmaceutical, food stuff industries and in hospitals. There are two standards widely used for HEPA filters; the EN 1822 standards published by the European Union, CEN (European Committee for Standardization) and the US based IEST standard (Institute of Environmental Sciences and Technology. Both standards exhibit some differences in the definitions of efficiency and its measurement methods. While IEST standard defines efficiency at the grit diameter of 0.3 µm, the EN 1822 standard takes MPPS (Most Penetrating Particle Size) as the basis of its definition. That is, the most difficult grit size to catch up. On the other hand, while IEST suggests that photometer and grit counters be used for filter testing, in EN 1822 standard, only the grit (grain) counters are recommended for that purpose. In this study, powder holding capacities of H13 and H14 grade materials under the EN 779 standard are investigated experimentally by using activated carbon. Measurements were taken on an experimental set up based on the TS 932 standard. Filter efficiency was measured by injecting test powder at amounts predetermined in the standards into the filters at certain intervals. The data obtained showed that the powder holding capacities of the activated carbon filter are high enough to yield efficiency of around 90% and that the H13 and H14 filters exhibit high efficiency suitable for the standard used.

Keywords: activated carbon filters, HEPA filters, powder holding capacities, air conditioning systems

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Authors: Enhui Wang, Qingzhu Ou, Yan Tang, Xiaodong Guo

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As one of most popular polyanionic compounds in lithium-ion cathode materials, Li3V2(PO4)3 has always suffered from the low rate capability especially during 3~4.8V, which is considered to be related with the ion diffusion resistance and structural transformation during the Li+ de/intercalation. Here, as the change of cut-off voltages, cycling numbers and current densities, the process of SEI interfacial film’s formation-growing- destruction-repair on the surface of the cathode, the structural transformation during the charge and discharge, the de/intercalation kinetics reflected by the electrochemical impedance and the diffusion coefficient, have been investigated in detail. Current density, cycle numbers and cut-off voltage impacting on interfacial film and structure was studied specifically. Firstly, the matching between electrolyte and material was investigated, it turned out that the batteries with high voltage electrolyte showed the best electrochemical performance and high voltage electrolyte would be the best electrolyte. Secondly, AC impedance technology was used to study the changes of interface impedance and lithium ion diffusion coefficient, the results showed that current density, cycle numbers and cut-off voltage influenced the interfacial film together and the one who changed the interfacial properties most was the key factor. Scanning electron microscopy (SEM) analysis confirmed that the attenuation of discharge specific capacity was associated with the destruction and repair process of the SEI film. Thirdly, the X-ray diffraction was used to study the changes of structure, which was also impacted by current density, cycle numbers and cut-off voltage. The results indicated that the cell volume of Li3V2 (PO4 )3 increased as the current density increased; cycle numbers merely influenced the structure of material; the cell volume decreased first and moved back gradually after two Li-ion had been deintercalated as the charging cut-off voltage increased, and increased as the intercalation number of Li-ion increased during the discharging process. Then, the results which studied the changes of interface impedance and lithium ion diffusion coefficient turned out that the interface impedance and lithium ion diffusion coefficient increased when the cut-off voltage passed the voltage platforms and decreased when the cut-off voltage was between voltage platforms. Finally, three-electrode system was first adopted to test the activation energy of the system, the results indicated that the activation energy of the three-electrode system (22.385 KJ /mol) was much smaller than that of two-electrode system (40.064 KJ /mol).

Keywords: cut-off voltage, de/intercalation kinetics, solid electrolyte interphase film, structural transformation

Procedia PDF Downloads 285

Authors: Behzad Ali Khan, M. Zubair Akbar Qureshi

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The article analyzes the Darcy Forchheimer 2D Hybrid ferrofluid. The flow of a Hybrid ferrofluid is made due to an unsteady porous channel. The classical liquid water is treated as a based liquid. The flow in the permeable region is characterized by the Darcy-Forchheimer relation. Heat transfer phenomena are studied during the flow. The transformation of a partial differential set of equations into a strong ordinary differential frame is formed through appropriate variables. The numerical Shooting Method is executed for solving the simplified set of equations. In addition, a numerical analysis (ND-Solve) is utilized for the convergence of the applied technique. The influence of some flow model quantities like Pr (Prandtle number), r (porous medium parameter), F (Darcy-porous medium parameter), Re (Reynolds number), Pe (Peclet number) on velocity and temperature field are scrutinized and studied through sketches. Certain physical factors like f ''(η) (skin friction coefficient) and θ^'(η) (rate of heat transfer) are first derived and then presented through tables.

Keywords: darcy forcheimer, hybrid ferro fluid, porous medium, porous channel

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Authors: Gema Gómez-Casado, Alba Rodríguez-Muñoz, Virginia Mela-Rivas, Pallavi Kompella, Francisco José Tinahones-Madueña, Isabel Moreno-Indias, Almudena Ortega-Gómez

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Obesity is a high-priority health problem worldwide due to its high prevalence. The proportion of obese and overweight subjects in industrialized countries exceeds half of the population in most cases. Beyond the metabolic problem, obesity boosts inflammation levels in the organism. The gut microbiota, considered an organ by itself, controls a high variety of processes at a systemic level. In fact, the microbiota interacts closely with the immune system, being crucial in determining the maturation state of neutrophils, key effectors of the innate immune response. It is known that changes in the diet exert strong effects on the variety and activity of the gut microbiota. The effect that those changes have on the axis microbiota-immune response is an unexplored field. In this study, 10 patients with obesity (weight 114,3 ± 14,5Kg, BMI 40,47±3,66) followed a Mediterranean-hypocaloric diet for 3 months, reducing their initial weight by 12,71 ± 3%. A transplant of microbiota from these patients before and after the diet was performed into wild type “germ-free” mice (n=10/group), treated with antibiotics. Six weeks after the transplant, mice were euthanized, and the presence of cells from the innate immune system were analysed in different organs (bone marrow, blood, spleen, visceral adipose tissue, and intestine) by flow cytometry. No differences were observed in the number of myeloid cells in bone marrow, blood, spleen, or visceral adipose tissue of mice transplanted with patient’s microbiota before and after following the Mediterranean diet. However, the intestine of mice that received post-diet microbiota presented a marked decrease in the number of neutrophils (whose presence is associated with tissue inflammation), as well as macrophages. In line with these findings, intestine monocytes from mice with post-diet microbiota showed a less inflammatory profile (lower Ly6Gˡᵒʷ proportion of cells). These results point toward a decrease in the inflammatory state of the intestinal tissue, derived from changes in the gut microbiota, which occurred after a 3-month Mediterranean diet.

Keywords: obesity, nutrition, Mediterranean diet, gut microbiota, immune system

Procedia PDF Downloads 111

Authors: Scholz Heiko, Kuhne Petra, Heckenberger Gerd

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Problems during the calving period (December to May) often result in a high body condition score (BCS) at this time. At the end of the grazing period (frequently after early weaning), however, an increase of BCS can often be observed under German conditions. In the last eight weeks before calving, the body condition should be reduced or at least not increased. Rations with a higher amount of crude fiber can be used (rations with straw or late mowed grass silage). Fermentative digestion of fiber is slow and incomplete; that’s why the fermentative process in the rumen can be reduced over a long feeding time. Viewed in this context, feed intake of suckler cows (8 weeks before calving) in different rations and fermentation in the rumen should be checked by taking rumen fluid. Eight suckler cows (Charolais) were feeding a Total Mixed Ration (TMR) in the last eight weeks before calving and grass silage after calving. By the addition of straw (30 % [TMR1] vs. 60 % [TMR2] of dry matter) was varied the amount of crude fiber in the TMR (grass silage, straw, mineral) before calving. After calving of the cow's grass, silage [GS] was fed ad libitum, and the last measurement of rumen fluid took place on the pasture [PS]. Rumen fluid, plasma, body weight, and backfat thickness were collected. Rumen fluid pH was assessed using an electronic pH meter. Volatile fatty acids (VFA), sedimentation, methylene-blue and amount of infusorians were measured. From these 4 parameters, an “index of rumen fermentation” [IRF] in the rumen was formed. Fixed effects of treatment (TMR1, TMR2, GS and PS) and a number of lactations (3-7 lactations) were analyzed by ANOVA using SPSS Version 25.0 (significant by p ≤ 5 %). Rumen fluid pH was significant influenced by variants (TMR 1 by 6.6; TMR 2 by 6.9; GS by 6.6 and PS by 6.9) but was not affected by other effects. The IRF showed disturbed fermentation in the rumen by feeding the TMR 1+2 with a high amount of crude fiber (Score: > 10.0 points) and a very good environment for fermentation during grazing the pasture (Score: 6.9 points). Furthermore, significant differences were found for VFA, methylene blue and the number of infusorians. The use of rations with the high amount of crude fiber from weaning to calving may cause deviations from undisturbed fermentation in the rumen and adversely affect the utilization of the feed in the rumen.

Keywords: suckler cow, feeding systems, crude fiber, digestibilty of organic matter

Procedia PDF Downloads 127

Authors: Natalie Hoyer

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Bridges in both roadway and railway systems depend on bearings to ensure extended service life and functionality. These bearings enable proper load distribution from the superstructure to the substructure while permitting controlled movement of the superstructure. The design of bridge bearings, according to Eurocode DIN EN 1337 and the relevant sections of DIN EN 1993, increasingly requires the use of thick plates, especially for long-span bridges. However, these plate thicknesses exceed the limits specified in the national appendix of DIN EN 1993-2. Furthermore, compliance with DIN EN 1993-1-10 regulations regarding material toughness and through-thickness properties necessitates further modifications. Consequently, these standards cannot be directly applied to the selection of bearing materials without supplementary guidance and design rules. In this context, a recommendation was developed in 2011 to regulate the selection of appropriate steel grades for bearing components. Prior to the initiation of the research project underlying this contribution, this recommendation had only been available as a technical bulletin. Since July 2023, it has been integrated into guideline 804 of the German railway. However, recent findings indicate that certain bridge-bearing components are exposed to high fatigue loads, which necessitate consideration in structural design, material selection, and calculations. Therefore, the German Centre for Rail Traffic Research called a research project with the objective of defining a proposal to expand the current standards in order to implement a sufficient choice of steel material for bridge bearings to avoid brittle fracture, even for thick plates and components subjected to specific fatigue loads. The results obtained from theoretical considerations, such as finite element simulations and analytical calculations, are validated through large-scale component tests. Additionally, experimental observations are used to calibrate the calculation models and modify the input parameters of the design concept. Within the large-scale component tests, a brittle failure is artificially induced in a bearing component. For this purpose, an artificially generated initial defect is introduced at the previously defined hotspot into the specimen using spark erosion. Then, a dynamic load is applied until the crack initiation process occurs to achieve realistic conditions in the form of a sharp notch similar to a fatigue crack. This initiation process continues until the crack length reaches a predetermined size. Afterward, the actual test begins, which requires cooling the specimen with liquid nitrogen until a temperature is reached where brittle fracture failure is expected. In the next step, the component is subjected to a quasi-static tensile test until failure occurs in the form of a brittle failure. The proposed paper will present the latest research findings, including the results of the conducted component tests and the derived definition of the initial crack size in bridge bearings.

Keywords: bridge bearings, brittle fracture, fatigue, initial crack size, large-scale tests

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Authors: Tytus Tulwin, Adam Majczak

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In aviation most important systems that impact the aircraft flight safety are duplicated. The ASz-62IR aircraft radial engine consists of two spark plugs powered by two separate magnetos. The relative difference in spark timing has an influence on the combustion process. The retardation of the second spark relative to the first spark was analyzed. The CFD simulation was developed as a multicycle transient model. Two independent spark sources imitate two flame fronts after an ignition period. It makes the combustion process shorter but only for certain range of second spark retardation. The model was validated by the in-cylinder pressure comparison. Combustion parameters were analyzed for different second spark retardation values. It was found that the most advantageous ignition timing in means of performance is simultaneous ignition. Nevertheless, for this engine the ignition time of the second spark plug is greatly retarded eliminating the advantageous performance influence. The reason behind this is maintaining high ignition certainty for all engine running conditions and for whole operating rpm range. In aviation the engine reliability is more important than its performance. Introducing electronic ignition system can yield from simultaneous ignition timing by increasing the engine performance and providing good reliability for all flight conditions. This work has been financed by the Polish National Centre for Research and Development, INNOLOT, under Grant Agreement No. INNOLOT/I/1/NCBR/2013.

Keywords: CFD, combustion, ignition, simulation, timing

Procedia PDF Downloads 374

Authors: Naira Sahakyan, Margarit Petrosyan, Armen Trchounian

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One of the tasks in contemporary biotechnology, pharmacology and other fields of human activities is to obtain biologically active substances from plants. They are very essential in the treatment of many diseases due to their actually high therapeutic value without visible side effects. However, sometimes the possibility of obtaining the metabolites is limited due to the reduction of wild-growing plants. That is why the plant cell cultures are of great interest as alternative sources of biologically active substances. Besides, during the monitored cultivation, it is possible to obtain substances that are not synthesized by plants in nature. Isolated culture of Ajuga genevensis with high growth activity and ability of regeneration was obtained using MS nutrient medium. The agar-diffusion method showed that aqueous extracts of callus culture revealed high antimicrobial activity towards various gram-positive (Bacillus subtilis A1WT; B. mesentericus WDCM 1873; Staphylococcus aureus WDCM 5233; Staph. citreus WT) and gram-negative (Escherichia coli WKPM M-17; Salmonella typhimurium TA 100) microorganisms. The broth dilution method revealed that the minimal and half maximal inhibitory concentration values against E. coli corresponded to the 70 μg/mL and 140 μg/mL concentration of the extract respectively. According to the photochemiluminescent analysis, callus tissue extracts of leaf and root origin showed higher antioxidant activity than the same quantity of A. genevensis intact plant extract. A. genevensis intact plant and callus culture extracts showed no cytotoxic effect on K-562 suspension cell line of human chronic myeloid leukemia. The GC-MS analysis showed deep differences between the qualitative and quantitative composition of callus culture and intact plant extracts. Hexacosane (11.17%); n-hexadecanoic acid (9.33%); and 2-methoxy-4-vinylphenol (4.28%) were the main components of intact plant extracts. 10-Methylnonadecane (57.0%); methoxyacetic acid, 2-tetradecyl ester (17.75%) and 1-Bromopentadecane (14.55%) were the main components of A. genevensis callus culture extracts. Obtained data indicate that callus culture of A. genevensis can be used as an alternative source of biologically active substances.

Keywords: Ajuga genevensis, antibacterial activity, antioxidant activity, callus cultures

Procedia PDF Downloads 286

Authors: Hammad Majeed, Hanna Knuutila, Magne Hillestad, Hallvard F. Svendsen

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Formation of aerosols can cause serious complications in industrial exhaust gas cleaning processes. Small mist droplets and fog formed can normally not be removed in conventional demisting equipment because their submicron size allows the particles or droplets to follow the gas flow. As a consequence of this, aerosol based emissions in the order of grams per Nm³ have been identified from PCCC plants. The model predicts the droplet size, the droplet internal variable profiles, and the mass transfer fluxes as function of position in the absorber. The Matlab model is based on a subclass method of weighted residuals for boundary value problems named, orthogonal collocation method. This paper presents results describing the basic simulation tool for the characterization of aerosols formed in CO₂ absorption columns and describes how various entering droplets grow or shrink through an absorber and how their composition changes with respect to time. Below are given some preliminary simulation results for an aerosol droplet composition and temperature profiles.

Keywords: absorption columns, aerosol formation, amine emissions, internal droplet profiles, monoethanolamine (MEA), post combustion CO2 capture, simulation

Procedia PDF Downloads 232

Authors: Chuanzhi Chen, Wenjing Yu

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Parabolic cylindrical deployable antenna has the characteristics of wide cutting width, strong directivity, high gain, and easy automatic beam scanning. While, due to its large size, high flexibility, and strong coupling, the deployment process of parabolic cylindrical deployable antenna presents such problems as unsynchronized deployment speed, large local deformation and discontinuous switching of deployment state. A large deployable parabolic cylindrical antenna is taken as the research object, and the problem of unfolding process instability of cylindrical antenna is studied in the paper, which is caused by multiple factors such as multiple closed loops, elastic deformation, motion friction, and gap collision. Firstly, the multi-flexible system dynamics model of large-scale parabolic cylindrical antenna is established to study the influence of friction and elastic deformation on the stability of large multi-closed loop antenna. Secondly, the evaluation method of antenna expansion stability is studied, and the quantitative index of antenna configuration design is proposed to provide a theoretical basis for improving the overall performance of the antenna. Finally, through simulation analysis and experiment, the development dynamics and stability of large-scale parabolic cylindrical antennas are verified by in-depth analysis, and the principles for improving the stability of antenna deployment are summarized.

Keywords: multibody dynamics, expandable parabolic cylindrical antenna, stability, flexible deformation

Procedia PDF Downloads 133

Authors: Ajay Biswas, Swapan Bhaumik, Abhijit Bhowmik

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Present experiment has been carried out to study the microstructure of weldment obtained by submerged arc welding on mild steel plate at zero degree Celsius. To study this, bead on plate welding is done by submerged arc welding on the sample plate of heavy duty mild steel of designation IS 2062 grade B, fitted on the special fixture ensuring the plate temperature at zero degree Celsius. Sixteen numbers of such samples are welded by varying the most influencing parameters viz. travel speed, voltage, wire feed rate and electrode stick-out at four different levels. Taguchi’s design of experiment is applied by selecting Taguchi's L16 orthogonal array to restrict the number of experimental runs. Cross sectioned samples are polished and etched to view the weldment. Finally, different zone of the weldment is observed by optical microscope. From the type of microstructure of weldment it is concluded that submerged arc welding is feasible at zero degree Celsius on mild steel plate.

Keywords: Submerged Arc Welding, zero degree Celsius, Taguchi’s design of experiment, microstructure of weldment

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Authors: Phumlani Msomi, Patrick Nonjola, Patrick Ndungu, James Ramontja

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A series of quaternized poly (2.6 dimethyl – 1.4 phenylene oxide)/ polysulfone (QPPO/PSF) blend anion exchange membrane (AEM) were successfully fabricated and characterized for methanol alkaline fuel cell application. Zinc Oxide (ZnO) nanoparticles were introduced in the polymer matrix to enhance the intrinsic properties of the AEM. To confirm successful fabrication, FT-IR spectroscopy and nuclear magnetic resonance (¹H NMR and HMBC ¹⁵N NMR) were used. The membrane properties were enhanced by the addition of ZnO nanoparticles. The addition of ZnO nanoparticles resulted to a higher ion exchange capacity (IEC) of 3.72 mmol.g⁻¹and a 30-fold ion conductivity (IC) increase of the nanocomposite due to no (zero (0)) methanol permeability at 30 °C and increased water uptake. The QPPO/PSF/2% ZnO composite retained over 80 % of its initial IC when evaluated for alkaline stability at room temperature. The maximum power output reached for the membrane electrode assembly (MEA) constructed with QPPO/PSF/2%ZnO is 69 mW.cm⁻², which is about three times more than the parent QPPO membrane. The above results indicate that QPPO/PSF-ZnO is a good candidate as an anion exchange membrane for fuel cell application.

Keywords: anion exchange membrane, fuel cell, zinc oxide, nanocomposite

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Authors: Samuel Knox, Verdon Crann, Peyman Amiri, William Crowther

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There exists a shortage of open-source firmware for allowing researchers to focus on implementing high-level planning and control strategies for multi aerial robotic systems in simulation and experiment. Within this body of work, practical firmware is presented, which performs all supplementary tasks, including communications, pre and post-experiment procedures, and emergency safety measures. This allows researchers to implement high-level planning and control algorithms for path planning, traffic management, flight formation and swarming of aerial robots. The framework is built in Python using the MAVSDK library, which is compatible with flight controllers running PX4 firmware and onboard computers based on Linux. Communication is performed using Wi-Fi and the MQTT protocol, currently implemented using a centralized broker. Finally, a graphical user interface (GUI) has been developed to send general commands and monitor the agents. This framework enables researchers to prepare customized planning and control algorithms in a modular manner. Studies can be performed experimentally and in simulation using PX4 software in the loop (SITL) and the Gazebo simulator. An example experimental use case of the framework is presented using novel distributed planning and control strategies. The demonstration is performed using off-the-shelf components and minimal setup.

Keywords: aerial robotics, distributed framework, experimental, planning and control

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Authors: Kyu Jin Kim, Byung Kwan Oh, Hyo Seon Park

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The seismic responses-based structural health monitoring system has been performed to reduce seismic damage. The inter-story drift ratio which is the major index of the seismic capacity assessment is employed for estimating the seismic damage of buildings. Meanwhile, seismic response analysis to estimate the structural responses of building demands significantly high computational cost due to increasing number of high-rise and large buildings. To estimate the inter-story drift ratio of buildings from the earthquake efficiently, this paper suggests the estimation method of inter-story drift for buildings using an artificial neural network (ANN). In the method, the radial basis function neural network (RBFNN) is integrated with optimization algorithm to optimize the variable through evolutionary learning that refers to evolutionary radial basis function neural network (ERBFNN). The estimation method estimates the inter-story drift without seismic response analysis when the new earthquakes are subjected to buildings. The effectiveness of the estimation method is verified through a simulation using multi-degree of freedom system.

Keywords: structural health monitoring, inter-story drift ratio, artificial neural network, radial basis function neural network, genetic algorithm

Procedia PDF Downloads 317

Authors: Obed Asamoah

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Forests are very vital for human survival and our well-being. During the past years, the world has taken an increasingly significant role in the modification of the global environment. The high rate of deforestation in Ghana is of primary national concern as the forests provide many ecosystem services and functions that support the country’s predominantly agrarian economy and foreign earnings. Ghana forest is currently major source of carbon sink that helps to mitigate climate change. Ghana forests, both the reserves and off-reserves, are under pressure of deforestation. The causes of deforestation are varied but can broadly be categorized into anthropogenic and natural factors. For the anthropogenic factors, increased wood fuel collection, clearing of forests for agriculture, illegal and poorly regulated timber extraction, social and environmental conflicts, increasing urbanization and industrialization are the primary known causes for the loss of forests and woodlands. Mineral exploitation in the forest areas is considered as one of the major causes of deforestation in Ghana. Mining activities especially mining of gold by both the licensed mining companies and illegal mining groups who are locally known as "gallantly mining" also cause damage to the nation's forest reserves. Several works have been conducted regarding the causes of the high rate of deforestation in Ghana, major attention has been placed on illegal logging and using forest lands for illegal farming and mining activities. Less emphasis has been placed on the timber production companies on their harvesting methods in the forests in Ghana and other activities that are carried out in the forest. The main objective of the work is to find out the harvesting methods and the activities of the timber production companies and their effects on the forests in Ghana. Both qualitative and quantitative research methods were engaged in the research work. The study population comprised of 20 Timber industries (Sawmills) forest areas of Ghana. These companies were selected randomly. The cluster sampling technique was engaged in selecting the respondents. Both primary and secondary data were employed. In the study, it was observed that most of the timber production companies do not know the age, the weight, the distance covered from the harvesting to the loading site in the forest. It was also observed that old and heavy machines are used by timber production companies in their operations in the forest, which makes the soil compact prevents regeneration and enhances soil erosion. It was observed that timber production companies do not abide by the rules and regulations governing their operations in the forest. The high rate of corruption on the side of the officials of the Ghana forestry commission makes the officials relax and do not embark on proper monitoring on the operations of the timber production companies which makes the timber companies to cause more harm to the forest. In other to curb this situation the Ghana forestry commission with the ministry of lands and natural resources should monitor the activities of the timber production companies and sanction all the companies that make foul play in their activities in the forest. The commission should also pay more attention to the policy “fell one plant 10” to enhance regeneration in both reserves and off-reserves forest.

Keywords: companies, deforestation, forest, Ghana, timber

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Authors: Hassan Saffari;, Reza Askari Moghadam

Abstract:

In modern communication systems, it is highly demanded to achieve high performance with minimal power consumption. Low actuation voltage RF MEMS (Micro-Electro-Mechanical Systems) switches represent a significant advancement in this regard. These switches, with their ability to operate at lower voltages, offer promising solutions for enhancing connectivity while minimizing energy consumption. Microelectromechanical switches are good alternatives for electronic and mechanical switches due to their low insertion loss, high isolation, and fast switching speeds. They have attracted more attention in recent years. Most of the presented RF MEMS switches use electrostatic actuators due to their low power consumption. Low actuation voltage RF MEMS switches are among the important issues that have been investigated in research articles. The actuation voltage can be reduced by different methods. One usually implemented method is low spring constant structures. However, despite their numerous benefits, challenges remain in the widespread adoption of low-actuation voltage RF MEMS switches. Issues related to reliability, durability, and manufacturing scalability need to be addressed to realize their full potential in commercial applications. While overcoming certain challenges, their exceptional performance characteristics and compatibility with miniaturized electronic systems make them a promising choice for next-generation wireless communication and RF applications. In this paper, some previous works that proposed low-voltage actuation RF MEMS switches are investigated and analyzed.

Keywords: RF MEMS switches, low actuation voltage, small spring constant structures, electrostatic actuation

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Authors: H. Niranjan, S. Sivasankaran, Zailan Siri

Abstract:

This study investigates mixed convection heat transfer about a thin vertical plate in the presence of magnetohydrodynamic (MHD) and heat transfer effects in the porous medium. The fluid is assumed to be steady, laminar, incompressible and in two-dimensional flow. The nonlinear coupled parabolic partial differential equations governing the flow are transformed into the non-similar boundary layer equations, which are then solved numerically using the shooting method. The effects of the conjugate heat transfer parameter, the porous medium parameter, the permeability parameter, the mixed convection parameter, the magnetic parameter, and the thermal radiation on the velocity and temperature profiles as well as on the local skin friction and local heat transfer are presented and analyzed. The validity of the methodology and analysis is checked by comparing the results obtained for some specific cases with those available in the literature. The various parameters on local skin friction, heat and mass transfer rates are presented in tabular form.

Keywords: MHD, porous medium, soret/dufour, stagnation-point

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Authors: Amit Keshav

Abstract:

Waste bone, produced in large quantity (8-10 kg./day) from a slaughterhouse, could be a cheap (cost $0.20 per kg) substitute for commercial catalysts. In the present work, catalyst for esterification reaction was prepared from waste bone and characterized by various techniques. Bone was deoiled and then sulfonated. Fourier-transform infrared spectroscopy (FTIR) spectra of prepared catalyst predicted –OH vibration at 3416 and 1630 cm⁻¹, S-O stretching at 1124 cm⁻¹ and intense bands of hydroxypatite in a region between 500 and 700 cm⁻¹. X-ray diffraction (XRD) predicts peaks of hydroxyapatite, CaO, and tricalcium phosphate. Scanning electron microscope (SEM) was employed to reveal the presence of non-uniformity deposited fine particles on the catalyst surface that represents active acidic sites. The prepared catalyst was employed to study its performance on esterification reaction between acrylic acid and ethanol in a molar ratio of 1:1 at a set temperature of 60 °C. Results show an equilibrium conversion of 49% which is matched to the commercial catalysts employed in literature. Thus waste bone could be a good catalyst for acrylic acid removal from waste industrial streams via the process of esterification.Keywords— Heterogeneous catalyst, characterization, esterification, equilibrium conversion

Keywords: heterogeneous catalyst, characterization, esterification, equilibrium conversion

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Authors: Korban Oosthuizen, Robert C. Luckay

Abstract:

Due to the growing popularity of electric vehicles and the importance of cobalt as part of the cathode material for lithium-ion batteries, demand for this metal is on the rise. Recycling of the cathode materials by means of solvent extraction is an attractive means of recovering cobalt and easing the pressure on limited natural resources. In this study, a series of straight chain and macrocyclic diamine ligands were developed for the selective recovery of cobalt from the solution containing nickel and manganese by means of solvent extraction. This combination of metals is the major cathode material used in electric vehicle batteries. The ligands can be protonated and function as ion-pairing ligands targeting the anionic [CoCl₄]²⁻, a species which is not observed for Ni or Mn. Selectivity for Co was found to be good at very high chloride concentrations and low pH. Longer chains or larger macrocycles were found to enhance selectivity, and linear chains on the amide side groups also resulted in greater selectivity over the branched groups. The cation of the chloride salt used for adjusting chloride concentrations seems to play a major role in extraction through salting-out effects. The ligands developed in this study show good selectivity for Co over Ni and Mn but require very high chloride concentrations to function. This research does, however, open the door for further investigations into using diamines as solvent extraction ligands for the recovery of cobalt from spent lithium-ion batteries.

Keywords: hydrometallurgy, solvent extraction, cobalt, lithium-ion batteries

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Authors: Mohamed M. Ibrahima, Abdul Aziz A.AL Sahli, Ibrahim A. Alaraidh, Ali A. Al-Homaidan, E.M. Mostafa, G.A. EL-Gaaly

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Traditionally, in Middle Eastern countries, many cultures use chewing sticks of arak for medicinal purposes especially, for oral cleanliness care. It was used by Muslims for the treatment of teeth and highly recommended to be used by muslims during the whole day. Therefore, the present work aimed to determine the total phenolic content and total flavonoids in two Miswak extracts obtained from arak roots collected from two different localities in Saudi Arabia. They were extracted with aqueous ethanol (80%) and used to estimate in vitro their antioxidative abilities. The new findings showed that the two tested extracts contained significantly different amounts of both total phenolic content and total flavonoids. According to the increase of total phenolic contents and total flavonoids obtained from the two extracts, Miswak collected from the southern region was found to contain more contents than those collected from the middle region. The results of antioxidant activities of Miswak root extract obtained by using different in vitro methods were varied depending on the technique used. According to the malondialdehyde (MDA) method, hydrogen peroxide (H2O2) scavenging ability and 1,1-diphenyl-2-picrylhydrazyl (DPPH) methods, the two Miswak extracts exhibited to have high to very high antioxidant activities. Mostly, the values of antioxidant activities of Southern region have been shown to be always the highest.

Keywords: Arak, antioxidant, medicinal plants, Saudi Arabia

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Authors: Amela Ajanovic, Reinhard Haas

Abstract:

Electric vehicles (EVs) are considered as an important means to cope with current environmental problems in transport. However, their high capital costs and limited driving ranges state major barriers to a broader market penetration. The core objective of this paper is to investigate the future market prospects of various types of EVs from an economic and ecological point of view. Our method of approach is based on the calculation of total cost of ownership of EVs in comparison to conventional cars and a life-cycle approach to assess the environmental benignity. The most crucial parameters in this context are km driven per year, depreciation time of the car and interest rate. The analysis of future prospects it is based on technological learning regarding investment costs of batteries. The major results are the major disadvantages of battery electric vehicles (BEVs) are the high capital costs, mainly due to the battery, and a low driving range in comparison to conventional vehicles. These problems could be reduced with plug-in hybrids (PHEV) and range extenders (REXs). However, these technologies have lower CO₂ emissions in the whole energy supply chain than conventional vehicles, but unlike BEV they are not zero-emission vehicles at the point of use. The number of km driven has a higher impact on total mobility costs than the learning rate. Hence, the use of EVs as taxis and in car-sharing leads to the best economic performance. The most popular EVs are currently full hybrid EVs. They have only slightly higher costs and similar operating ranges as conventional vehicles. But since they are dependent on fossil fuels, they can only be seen as energy efficiency measure. However, they can serve as a bridging technology, as long as BEVs and fuel cell vehicle do not gain high popularity, and together with PHEVs and REX contribute to faster technological learning and reduction in battery costs. Regarding the promotion of EVs, the best results could be reached with a combination of monetary and non-monetary incentives, as in Norway for example. The major conclusion is that to harvest the full environmental benefits of EVs a very important aspect is the introduction of CO₂-based fuel taxes. This should ensure that the electricity for EVs is generated from renewable energy sources; otherwise, total CO₂ emissions are likely higher than those of conventional cars.

Keywords: costs, mobility, policy, sustainability,

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Authors: Yen Ling Liu, Shu-Fen Wu, Chen-Fuh Lam, I-Ling Tsai, Chia-Yu Chen

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Purpose: Nurse anesthetists are confronting extraordinarily high job stress in their daily practice, deriving from the fast-track anesthesia care, risk of perioperative complications, routine rotating shifts, teaching programs and interactions with the surgical team in the operating room. This study investigated the influence of work stress on the burnout and turnover intention of nurse anesthetists in a regional general hospital in Southern Taiwan. Methods: This was a descriptive correlational study carried out in 66 full-time nurse anesthetists. Data was collected from March 2017 to June 2017 by in-person interview, and a self-administered structured questionnaire was completed by the interviewee. Outcome measurements included the Practice Environment Scale of the Nursing Work Index (PES-NWI), Maslach Burnout Inventory (MBI) and nursing staff turnover intention. Numerical data were analyzed by descriptive statistics, independent t test, or one-way ANOVA. Categorical data were compared using the chi-square test (x²). Datasets were computed with Pearson product-moment correlation and linear regression. Data were analyzed by using SPSS 20.0 software. Results: The average score for job burnout was 68.7916.67 (out of 100). The three major components of burnout, including emotional depletion (mean score of 26.32), depersonalization (mean score of 13.65), and personal(mean score of 24.48). These average scores suggested that these nurse anesthetists were at high risk of burnout and inversely correlated with turnover intention (t = -4.048, P < 0.05). Using linear regression model, emotional exhaustion and depersonalization were the two independent factors that predicted turnover intention in the nurse anesthetists (19.1% in total variance). Conclusion/Implications for Practice: The study identifies that the high risk of job burnout in the nurse anesthetists is not simply derived from physical overload, but most likely resulted from the additional emotional and psychological stress. The occurrence of job burnout may affect the quality of nursing work, and also influence family harmony, in turn, may increase the turnover rate. Multimodal approach is warranted to reduce work stress and job burnout in nurse anesthetists to enhance their willingness to contribute in anesthesia care.

Keywords: anesthesia nurses, burnout, job, turnover intention

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Authors: Farzana Rahman, Mohammed Hossain Ezaz, Dipak Halder, Proshanta Mondal

Abstract:

Site safety is an important function regardless of project size. A key goal, which must be met for a successful project, is to finish the project with a good safety record. Construction safety is an important issue in all over the world. Today, developed countries strictly follow the safety procedure to avoid any hazard, accident or fatality. However, for a least developed country like Bangladesh, still accidents and fatalities are quite high due to lack of safety management. With the increased volume of construction work in Bangladesh, the need for proper attention in safety issues has become essential for human, economic and other consideration. Recently lots of accidents are taking place in construction sites of Bangladesh causing severe injury to death to the workers and pedestrians. There are a number of reasons/factors that these high numbers are widespread to the construction industry that are not found in most other businesses. The objective of this research work is to identify and explore the various factor that affect the construction site safety in Bangladesh. A questionnaire surveys was conducted to the reputed construction companies of Bangladesh to examine the present safety situation in construction sites. Nine factors were selected for the survey. The finding shows that 78% of organizations’ from the respondents are conscious about the safety procedure and they usually provide safety measures for the workers. Promotion of safety measures at the working site results in a better working environment, higher productivity and greater contentment among the workers.

Keywords: construction sites, fatalities, safety issues, safety situation

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Authors: Gideon Ndubuisi

Abstract:

It is widely acknowledged that the quality of a country’s export matters more decisively than the quantity it exports. Hence, understanding the drivers of exported goods’ quality is a relevant policy question. Among other things, product quality upgrading is a considerable cost uncertainty venture that can be undertaken by an entrepreneur. Once a product is successfully upgraded, however, others can imitate the product, and hence, the returns to the pioneer entrepreneur are socialized. Along with this line, a government policy such as intellectual property rights (IPRs) protection which lessens the non-appropriability problem and incentivizes cost discovery investments becomes both a panacea in addressing the market failure and a sine qua non for an entrepreneur to engage in product quality upgrading. In addendum, product quality upgrading involves complex tasks which often require a lot of knowledge and technology sharing beyond the bounds of the firm thereby creating rooms for knowledge spillovers and imitations. Without an institution that protects upstream suppliers of knowledge and technology, technology masking occurs which bids up marginal production cost and product quality fall. Despite these clear associations between IPRs and product quality upgrading, the surging literature on the drivers of the quality of exported goods has proceeded almost in isolation of IPRs protection as a determinant. Consequently, the current study uses a difference-in-difference method to evaluate the effects of IPRs reforms on the quality of exported goods in 16 developing countries over the sample periods of 1984-2000. The study finds weak evidence that IPRs reforms increase the quality of all exported goods. When the industries are sorted into high and low-patent sensitive industries, however, we find strong indicative evidence that IPRs reform increases the quality of exported goods in high-patent sensitive sectors both in absolute terms and relative to the low-patent sensitive sectors in the post-reform period. We also obtain strong indicative evidence that it brought the quality of exported goods in the high-patent sensitive sectors closer to the quality frontier. Accounting for time-duration effects, these observed effects grow over time. The results are also largely consistent when we consider the sophistication and complexity of exported goods rather than just quality upgrades.

Keywords: exports, export quality, export sophistication, intellectual property rights

Procedia PDF Downloads 108