Search results for: thermal materials

Authors: Lynda K. Eneh, Okal N. Mike, Anna-Karin Borg-Karlson, Ulrike Fillinger, Jenny M. Lindh

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The responses of individual gravid Anopheles gambiae sensu stricto (s.s.) to hay infusion volatiles were evaluated under laboratory conditions. Such infusions have long been known to be effective baits for monitoring mosquitoes that vector arboviral and filarial diseases but have previously not been tested for malaria vectors. Hay infusions were prepared by adding sun-dried Bermuda grass to lake water and leaving the mixture in a covered bucket for three days. The proportions of eggs laid by gravid An. gambiae s.s. in diluted (10%) and concentrated infusions ( ≥ 25%) was compared to that laid in lake water in two-choice egg-count bioassays. Furthermore, with the aim to develop a method that can be used to collect volatiles that influence the egg-laying behavior of malaria mosquitoes, different volatile trapping methods were investigated. Two different polymer-traps eluted using two different desorption methods and three parameters were investigated. Porapak®-Q traps and solvent desorption was compared to Tenax®-TA traps and thermal desorption. The parameters investigated were: collection time (1h vs. 20h), addition of salt (0.15 g/ml sodium chloride (NaCl) vs. no NaCl), and stirring the infusion (0 vs. 300 rpm). Sample analysis was with gas chromatography-mass spectrometry (GC-MS). An. gambiae s.s was ten times less likely to lay eggs in concentrated hay infusion than in lake water. The volatiles were best characterized by thermally desorbed Tenax traps, collected for 20 hours from infusion aliquots with sodium chloride added. Ten volatiles identified from headspace and previously indicated as putative oviposition semiochemicals for An. gambiae s.s. or confirmed semiochemicals for other mosquito species were tested in egg-count bioassays. Six of these (3-methylbutanol, phenol, 4-methylphenol, nonanal, indole and 3-methylindole), when added to lake water, were avoided for egg-laying when lake water was offered as the alternative in dual-choice egg count bioassays. These compounds likely contribute to the unfavorable oviposition responses towards hay infusions. This difference in oviposition response of different mosquito species should be considered when designing control measures.

Keywords: Anopheles gambiae, oviposition behaviour, egg-count cage bioassays, hay infusions, volatile detection, semiochemicals

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Authors: Mekhannene Amine

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In this paper, we began in the first step by two-dimensional simulation of a CIGS solar cell, in order to increase the current record efficiency of 20.48% for a single CIGS cell. Was created by utilizing a set of physical and technological parameters a solar cell of reference (such as layer thicknesses, gallium ratio, doping levels and materials properties) documented in bibliography and very known in the experimental field. This was accomplished through modeling and simulation using Atlas SILVACO-TCAD, an tool two and three dimensions very powerful and very adapted. This study has led us to determine the influence of different environmental parameters such as illumination (G) and temperature (T). In the second step, we continued our study by determining the influence of physical parameters (the acceptor of concentration NA) and geometric (thickness t) of the CIGS absorber layer, were varied to produce an optimum efficiency of 24.36%. This approach is promising to produce a CIGS classic solar cell to conduct a maximum performance.

Keywords: solar cell, cigs, photovoltaic generator, illumination, temperature, Atlas SILVACO-TCAD

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Authors: Pavana Basavakumar, Devadas Bhat

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Diabetes is a disease which often goes undiagnosed until its secondary effects are noticed. Early detection of the disease is necessary to avoid serious consequences which could lead to the death of the patient. Conventional invasive tests for screening of diabetes are mostly painful, time consuming and expensive. There’s also a risk of infection involved, therefore it is very essential to develop non-invasive methods to screen and estimate the level of blood glucose. Extensive research is going on with this perspective, involving various techniques that explore optical, electrical, chemical and thermal properties of the human body that directly or indirectly depend on the blood glucose concentration. Thus, non-invasive blood glucose monitoring has grown into a vast field of research. In this project, an attempt was made to device a prototype for screening of diabetes by measuring electrical impedance of the skin and building a model to predict a patient’s condition based on the measured impedance. The prototype developed, passes a negligible amount of constant current (0.5mA) across a subject’s index finger through tetra polar silver electrodes and measures output voltage across a wide range of frequencies (10 KHz – 4 MHz). The measured voltage is proportional to the impedance of the skin. The impedance was acquired in real-time for further analysis. Study was conducted on over 75 subjects with permission from the institutional ethics committee, along with impedance, subject’s blood glucose values were also noted, using conventional method. Nonlinear regression analysis was performed on the features extracted from the impedance data to obtain a model that predicts blood glucose values for a given set of features. When the predicted data was depicted on Clarke’s Error Grid, only 58% of the values predicted were clinically acceptable. Since the objective of the project was to screen diabetes and not actual estimation of blood glucose, the data was classified into three classes ‘NORMAL FASTING’,’NORMAL POSTPRANDIAL’ and ‘HIGH’ using linear Support Vector Machine (SVM). Classification accuracy obtained was 91.4%. The developed prototype was economical, fast and pain free. Thus, it can be used for mass screening of diabetes.

Keywords: Clarke’s error grid, electrical impedance of skin, linear SVM, nonlinear regression, non-invasive blood glucose monitoring, screening device for diabetes

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Authors: Wenya Shu, Ilinca Stanciulescu

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Carbon nanotubes (CNTs) possess attractive properties, such as high stiffness and strength, and high thermal and electrical conductivities, making them promising filler in multifunctional nanocomposites. Although CNTs can be efficient reinforcements, the expected level of mechanical performance of CNT-polymers is not often reached in practice due to the poor mechanical behavior of the CNT-polymer interfaces. It is believed that the interactions of CNT and polymer mainly result from the Van der Waals force. The interface debonding is a fracture and delamination phenomenon. Thus, the cohesive zone modeling (CZM) is deemed to give good capture of the interface behavior. The detailed, cohesive zone modeling provides an option to consider the CNT-matrix interactions, but brings difficulties in mesh generation and also leads to high computational costs. Homogenized models that smear the fibers in the ground matrix and treat the material as homogeneous are studied in many researches to simplify simulations. But based on the perfect interface assumption, the traditional homogenized model obtained by mixing rules severely overestimates the stiffness of the composite, even comparing with the result of the CZM with artificially very strong interface. A mechanical model that can take into account the interface debonding and achieve comparable accuracy to the CZM is thus essential. The present study first investigates the CNT-matrix interactions by employing cohesive zone modeling. Three different coupled CZM laws, i.e., bilinear, exponential and polynomial, are considered. These studies indicate that the shapes of the CZM constitutive laws chosen do not influence significantly the simulations of interface debonding. Assuming a bilinear traction-separation relationship, the debonding process of single CNT in the matrix is divided into three phases and described by differential equations. The analytical solutions corresponding to these phases are derived. A homogenized model is then developed by introducing a parameter characterizing interface sliding into the mixing theory. The proposed mechanical model is implemented in FEAP8.5 as a user material. The accuracy and limitations of the model are discussed through several numerical examples. The CZM simulations in this study reveal important factors in the modeling of CNT-matrix interactions. The analytical solutions and proposed homogenized model provide alternative methods to efficiently investigate the mechanical behaviors of CNT/polymer composites.

Keywords: carbon nanotube, cohesive zone modeling, homogenized model, interface debonding

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Authors: Khaled Elbehiery, Hussam Elbehiery

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Smart cities are a framework of technologies along with sustainable infrastructure to provide their citizens an improved quality of life, safer environment, affordability, and more, which in turn helps with the society's economic growth. The proposed research will focus on the primary building block of the smart city; the infrastructure of the house itself. The traditional method of building houses has been, for a long time, nothing but a costly manufacturing process, and consequently, buying a house becomes not an option for everyone anymore. The smart cities' Modular Houses are not using traditional building construction materials; the design reduces the common lengthy construction times and associated high costs. The Modular Houses are technological homes, low-cost and customizable based on a family's requirements. In addition, the Modular Houses are environmentally friendly and healthy enough to assist with the pandemic situation.

Keywords: smart cities, modular houses, single-unit property, multi-unit property, mobility features, chain-supply, livable environment, carbon footprint

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Authors: Farah El Mohtadi, Richard d'Arcy, Nicola Tirelli

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Since 40 years, poly (ethylene glycol) (PEG) has been the gold standard in biomaterials and drug delivery, because of its combination of chemical and biological inertness. However, the possibility of its breakdown under oxidative conditions and the demonstrated development of anti-PEG antibodies highlight the necessity to develop carriers based on materials with increased stability in a challenging biological environment. Here, we describe the synthesis of polysulfide via anionic ring-opening polymerization. In vitro, the synthesized polymer was characterized by low toxicity and a level of complement activation (in human plasma) and macrophage uptake slightly lower than PEG and poly (2‐methyl-2‐oxazoline) (PMOX), of a similar size. Importantly, and differently from PEG, on activated macrophages, the synthesized polymer showed a strong and dose-dependent ROS scavenging activity, which resulted in the corresponding reduction of cytokine production. Therefore, the results from these studies show that polysulfide is highly biocompatible and are potential candidates to be used as an alternative to PEG for various applications in nanomedicine.

Keywords: PEG, low toxicity, ROS scavenging, biocompatible

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Authors: Sangwoo Han, Saeed Khaleghi Rahimian, Ying Liu

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Vehicle electrification is gaining momentum, and many car manufacturers promise to deliver more electric vehicle (EV) models to consumers in the coming years. In controlling the battery pack, the battery management system (BMS) must maintain optimal battery performance while ensuring the safety of a battery pack. Tasks related to battery performance include determining state-of-charge (SOC), state-of-power (SOP), state-of-health (SOH), cell balancing, and battery charging. Safety related functions include making sure cells operate within specified, static and dynamic voltage window and temperature range, derating power, detecting faulty cells, and warning the user if necessary. The BMS often utilizes an RC circuit model to model a Li-ion cell because of its robustness and low computation cost among other benefits. Because an equivalent circuit model such as the RC model is not a physics-based model, it can never be a prognostic model to predict battery state-of-health and avoid any safety risk even before it occurs. A physics-based Li-ion cell model, on the other hand, is more capable at the expense of computation cost. To avoid the high computation cost associated with a full-order model, many researchers have demonstrated the use of a single particle model (SPM) for BMS applications. One drawback associated with the single particle modeling approach is that it forces to use the average current density in the calculation. The SPM would be appropriate for simulating drive cycles where there is insufficient time to develop a significant current distribution within an electrode. However, under a continuous or high-pulse electrical load, the model may fail to predict cell voltage or Li⁺ plating potential. To overcome this issue, a multi-particle reduced-order model is proposed here. The use of multiple particles combined with either linear or nonlinear charge-transfer reaction kinetics enables to capture current density distribution within an electrode under any type of electrical load. To maintain computational complexity like that of an SPM, governing equations are solved sequentially to minimize iterative solving processes. Furthermore, the model is validated against a full-order model implemented in COMSOL Multiphysics.

Keywords: battery management system, physics-based li-ion cell model, reduced-order model, single-particle and multi-particle model

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Authors: Rudolf L. Kanyane, Nicolaus Malatji, Patritia A. Popoola

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Tribological failure of materials during application can lead to catastrophic events which also carry economic penalties. High entropy alloys (HEAs) have shown outstanding tribological properties in applications such as mechanical parts were moving parts under high friction are required. This work aims to investigate the effect of sintering temperature on microhardness properties and tribological properties of novel equiatomic TiAlMoSiW HEAs fabricated via spark plasma sintering. The effect of Spark plasma sintering temperature on morphological evolution and phase formation was also investigated. The microstructure and the phases formed for the developed HEAs were examined using scanning electron microscopy (SEM) and X-ray diffractometry (XRD) respectively. The microhardness and tribological properties were studied using a diamond base microhardness tester Rtec tribometer. The developed HEAs showed improved mechanical properties as the sintering temperature increases.

Keywords: sintering, high entropy alloy, microhardness, tribology

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Authors: I. Algul, G. Akgun, H. Kurtaran

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Dynamic analysis of composite doubly curved panels with variable thickness subjected to different pulse types using Generalized Differential Quadrature method (GDQ) is presented in this study. Panels with variable thickness are used in the construction of aerospace and marine industry. Giving variable thickness to panels can allow the designer to get optimum structural efficiency. For this reason, estimating the response of variable thickness panels is very important to design more reliable structures under dynamic loads. Dynamic equations for composite panels with variable thickness are obtained using virtual work principle. Partial derivatives in the equation of motion are expressed with GDQ and Newmark average acceleration scheme is used for temporal discretization. Several examples are used to highlight the effectiveness of the proposed method. Results are compared with finite element method. Effects of taper ratios, boundary conditions and loading type on the response of composite panel are investigated.

Keywords: differential quadrature method, doubly curved panels, laminated composite materials, small displacement

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Authors: Luís Felipe da Cunha Mendonça

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Normally, rural roads do not have any type of coating, and when they have any coating, they have a high maintenance cost due to the characteristics of natural materials. The Steel Aggregate has specific technical characteristics, which considerably reduce the maintenance costs of rural roads with the execution of the Primary Coating. For use as a primary coating, it must be mixed with clay due to the physical-chemical properties of the material. The application is mainly in the Primary Coating of rural roads due to the cementitious property in the presence of water, offering greater resistance to wear caused by traffic and consequently a longer useful life of the coating. The Steel Aggregate executed on rural roads has reduced particulate emissions and offers normal traffic in any weather condition, as well as creating sustainability. Contribute to the quality of life of communities through improvements in the conditions of rural and urban unpaved roads. Leading to substantial savings in maintenance. Because the durability, if applied correctly, is about 3 years, but if annual monitoring is carried out, it can be extended for more than 5 years.

Keywords: steel slag, co-product, primary coating, steel aggregate

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Authors: S. Athiralakshmi, B.E. Bhojaraja, U. Pruthviraj

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In agriculture, remote sensing is applied for monitoring of plant development, evaluating of physiological processes and growth conditions. Especially valuable are the spatio-temporal aspects of the remotely sensed data in detecting crop state differences and stress situations. In this study, hyperion imagery is used for classifying arecanut crops based on their age so that these maps can be used in yield estimation of crops, irrigation purposes, applying fertilizers etc. Traditional hard classifiers assigns the mixed pixels to the dominant classes. The proposed method uses a sub pixel level classifier called linear spectral unmixing available in ENVI software. It provides the relative abundance of surface materials and the context within a pixel that may be a potential solution to effectively identifying the land-cover distribution. Validation is done referring to field spectra collected using spectroradiometer and the ground control points obtained from GPS.

Keywords: FLAASH, Hyperspectral remote sensing, Linear Spectral Unmixing, Spectral Angle Mapper Classifier.

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Authors: Abbas Vahedian, Rijun Shrestha, Keith Crews

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In recent years, fibre reinforced polymers as applications of strengthening materials have received significant attention by civil engineers and environmentalists because of their excellent characteristics. Currently, these composites have become a mainstream technology for strengthening of infrastructures such as steel, concrete and more recently, timber and masonry structures. However, debonding is identified as the main problem which limit the full utilisation of the FRP material. In this paper, a preliminary analysis of factors affecting bond strength of FRP-to-concrete and timber bonded interface has been conducted. A novel theoretical method through regression analysis has been established to evaluate these factors. Results of proposed model are then assessed with results of pull-out tests and satisfactory comparisons are achieved between measured failure loads (R² = 0.83, P < 0.0001) and the predicted loads (R² = 0.78, P < 0.0001).

Keywords: debonding, fibre reinforced polymers (FRP), pull-out test, stepwise regression analysis

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Authors: E Tolufase

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The demand, high costs and health implications of using energy derived from hydrocarbon compound have necessitated the continuous search for alternative source of energy. The World energy market is facing some challenges viz: depletion of fossil fuel reserves, population explosion, lack of energy security, economic and urbanization growth and also, in Nigeria some rural areas still depend largely on wood, charcoal, kerosene, petrol among others, as the sources of their energy. To overcome these short falls in energy supply and demand, as well as taking into consideration the risks from global climate change due to effect of greenhouse gas emissions and other pollutants from fossil fuels’ combustion, brought a lot of attention on efficiently harnessing the renewable energy sources. A very promising among the renewable energy resources for a clean energy technology for power production, vehicle and domestic usage is biogas. Therefore, optimization of biogas yield and quality is imperative. Hence, this study investigated yield and quality of biogas using low cost bio-digester and combination of various feed stocks referred to as co-digestion. Batch/Discontinuous Bio-digester type was used because it was cheap, easy, plausible and appropriate for different substrates used to get the desired results. Three substrates were used; cow dung, chicken droppings and lemon grass digested in five separate 21 litre digesters, A, B, C, D, and E and the gas collection system was designed using locally available materials. For single digestion we had; cow dung, chicken droppings, lemon grass, in Bio-digesters A, B, and C respectively, the co-digested three substrates in different mixed ratio 7:1:2 in digester D and E in ratio 5:3:2. The respective feed-stocks materials were collected locally, digested and analyzed in accordance with standard procedures. They were pre-fermented for a period of 10 days before being introduced into the digesters. They were digested for a retention period of 28 days, the physiochemical parameters namely; pressure, temperature, pH, volume of the gas collector system and volume of biogas produced were all closely monitored and recorded daily. The values of pH and temperature ranged 6.0 - 8.0, and 220C- 350C respectively. For the single substrate, bio-digester A(Cow dung only) produced biogas of total volume 0.1607m3(average volume of 0.0054m3 daily),while B (Chicken droppings ) produced 0.1722m3 (average of 0.0057m3 daily) and C (lemon grass) produced 0.1035m3 (average of 0.0035m3 daily). For the co-digested substrates in bio-digester D the total biogas produced was 0.2007m³ (average volume of 0.0067m³ daily) and bio-digester E produced 0.1991m³ (average volume of 0.0066m³ daily) It’s obvious from the results, that combining different substrates gave higher yields than when a singular feed stock was used and also mixing ratio played some roles in the yield improvement. Bio-digesters D and E contained the same substrates but mixed with different ratios, but higher yield was noticed in D with mixing ratio of 7:1:2 than in E with ratio 5:3:2.Therefore, co-digestion of substrates and mixing proportions are important factors for biogas production optimization.

Keywords: anaerobic, batch, biogas, biodigester, digestion, fermentation, optimization

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Authors: A. Fettahoglu

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Theory of viscoelasticity is used by many researchers to represent the behavior of many materials such as pavements on roads or bridges. Several researches used analytical methods and rheology to predict the material behaviors of simple models. Today, more complex engineering structures are analyzed using Finite Element Method, in which material behavior is embedded by means of three dimensional viscoelastic material laws. As a result, structures of unordinary geometry and domain can be analyzed by means of Finite Element Method and three dimensional viscoelastic equations. In the scope of this study, rheological models embedded in ANSYS, namely, generalized Maxwell model and Prony series, which are two methods used by ANSYS to represent viscoelastic material behavior, are presented explicitly. Afterwards, a guide is illustrated to ease using of viscoelasticity tool in ANSYS.

Keywords: ANSYS, generalized Maxwell model, finite element method, Prony series, viscoelasticity, viscoelastic material curve fitting

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Authors: Chadel Meriem, Bensmaine Souhila, Chadel Asma, Bouchikhi Chaima

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The Methylammonium Lead Iodide CH3NH3PbI3 is used in solar cell as an absorber layer since 2009. The efficiencies of these technologies have increased from 3.8% in 2009 to 29.15% in 2019. So, these technologies Methylammonium Lead Iodide is promising for the development of high-performance photovoltaic applications. Due to the high cost of the experimental of the solar cells, researchers have turned to other methods like numerical simulation. In this work, we evaluate and simulate the performance of a CH₃NH₃PbI₃ lead-based perovskite solar cell when the amount of materials of absorber layer is reduced. We show that the reducing of thickness the absorber layer influent on performance of the solar cell. For this study, the one-dimensional simulation program, SCAPS-1D, is used to investigate and analyze the performance of the perovskite solar cell. After optimization, maximum conversion efficiency was achieved with 300 nm in absorber layer.

Keywords: methylammonium lead Iodide, perovskite solar cell, caracteristic J-V, effeciency

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Authors: Rit M., Girard R., Villot J., Thorel M.

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In a scenario of extensive residential housing renovation, stakeholders need models that support decision-making through a deep understanding of the existing building stock and accurate energy demand simulations. To address this need, we have modified an optimization model using open data that enables the study of renovation strategies at both territorial and national scales. This approach provides (1) a definition of a strategy to simplify decision trees from theoretical combinations, (2) input to decision makers on real-world renovation constraints, (3) more reliable identification of energy-saving measures (changes in technology or behaviour), and (4) discrepancies between currently planned and actually achieved strategies. The main contribution of the studies described in this document is the geographic scale: all residential buildings in the areas of interest were modeled and simulated using national data (geometries and attributes). These buildings were then renovated, when necessary, in accordance with the environmental objectives, taking into account the constraints applicable to each territory (number of renovations per year) or at the national level (renovation of thermal deficiencies (Energy Performance Certificates F&G)). This differs from traditional approaches that focus only on a few buildings or archetypes. This model can also be used to analyze the evolution of a building stock as a whole, as it can take into account both the construction of new buildings and their demolition or sale. Using specific case studies of French territories, this paper highlights a significant discrepancy between the strategies currently advocated by decision-makers and those proposed by our optimization model. This discrepancy is particularly evident in critical metrics such as the relationship between the number of renovations per year and achievable climate targets or the financial support currently available to households and the remaining costs. In addition, users are free to seek optimizations for their building stock across a range of different metrics (e.g., financial, energy, environmental, or life cycle analysis). These results are a clear call to re-evaluate existing renovation strategies and take a more nuanced and customized approach. As the climate crisis moves inexorably forward, harnessing the potential of advanced technologies and data-driven methodologies is imperative.

Keywords: residential housing renovation, MILP, energy demand simulations, data-driven methodology

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Authors: Kinga Anna Gajda

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The aim of the paper is presented the results of the research project titled: Regional or trans-regional cultural education using the example of museums. In the frame of the project there were prepared: Qualitative and quantitative analysis of the level of schools’ use of museum programs in the period 2010-2015; Qualitative and quantitative analysis of interprovincial co-operation between schools and cultural institutions; intevied and questionnaries. That was a research materials. Informal education may include classes that use visual culture - museum lessons. The paper will examine what range of programs is offered schools by the museums. On the basis of the conducted analysis, the paper will verify what programs addressing the schools are directly coincided with the material taught in schools or as a supplement to existing curriculum. The paper will answer the question is the museum-based education the part of school education, the teaching parallel or a separate category of teaching.

Keywords: museum-based education, school, parallel teaching, curriculum

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Authors: Ivana Loncarevic, Biljana Pajin, Ivana Vasiljevic, Milana Lazovic, Danica Mrkajic, Aleksandar Fises, Strahinja Kovacevic

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Biscuits belong to a group of flour-confectionery products that are considerably consumed worldwide. The basic raw material for their production is wheat flour or integral flour as a nutritionally highly valuable component. However, this raw material is also a potential source of contamination since it may contain the residues of biochemical compounds originating from plant and soil protection agents. Therefore, it is necessary to examine the health safety of both raw materials and final products. The aim of this research was to examine the content of undesirable residues of pesticides (mostly organochlorine pesticides, organophosphorus pesticides, carbamate pesticides, triazine pesticides, and pyrethroid pesticides) in 30 different biscuit samples of domestic origin present on the Vojvodina market using Gas Chromatograph Thermo ISQ/Trace 1300. The results showed that all tested samples had the limit of detection of pesticide content below 0.01 mg/kg, indicating that this type of confectionary products is not contaminated with pesticides.

Keywords: biscuits, pesticides, contamination, quality

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Authors: Rapelang E. Simon, Thebeetsile A. Olebetse, Joseph R. Maritinkole, Ruth O. Moleleke

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The P and S wave seismic velocity ratios (Vp/Vs) of some aftershocks are investigated using the method ofWadati diagrams. These aftershocks occurred after the 3rdApril 2017 Botswana’s Mw 6.5 earthquake and were recorded by the Network of Autonomously Recording Seismographs (NARS)-Botswana temporary network deployed from 2013 to 2018. In this paper, P and S wave data with good signal-to-noise ratiofrom twenty events of local magnitude greater or equal to 4.0are analysed with the Seisan software and used to infer properties of the upper crust in Botswana. The Vp/Vsratiosare determined from the travel-times of body waves and then converted to Poisson’s ratio, which is useful in determining the physical state of the subsurface materials. The Vp/Vs ratios of the upper crust in Botswana show regional variations from 1.70 to 1.77, with an average of 1.73. The Poisson’s ratios range from 0.24to 0.27 with an average of 0.25 and correlate well with the geological structures in Botswana.

Keywords: Botswana, earthquake, poisson's ratio, seismic velocity, Vp/Vs ratio

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Authors: Geeta Kumari, Prabu Vairakannu

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Underground coal gasification (UCG) technology is an efficient and an economic in-situ clean coal technology, which converts unmineable coals into calorific valuable gases. This technology avoids ash disposal, coal mining, and storage problems. CO₂ gas can be a potential gasifying medium for UCG. CO₂ is a greenhouse gas and, the liberation of this gas to the atmosphere from thermal power plant industries leads to global warming. Hence, the capture and reutilization of CO₂ gas are crucial for clean energy production. However, the reactivity of high ash Indian coals with CO₂ needs to be assessed. In the present study, two varieties of Indian coals (low ash and high ash) are used for thermogravimetric analyses (TGA). Two low ash north east Indian coals (LAC) and a typical high ash Indian coal (HAC) are procured from the coal mines of India. Low ash coal with 9% ash (LAC-1) and 4% ash (LAC-2) and high ash coal (HAC) with 42% ash are used for the study. TGA studies are carried out to evaluate the activation energy for pyrolysis and gasification of coal under N₂ and CO₂ atmosphere. Coats and Redfern method is used to estimate the activation energy of coal under different temperature regimes. Volumetric model is assumed for the estimation of the activation energy. The activation energy estimated under different temperature range. The inherent properties of coals play a major role in their reactivity. The results show that the activation energy decreases with the decrease in the inherent percentage of coal ash due to the ash layer hindrance. A reverse trend was observed with volatile matter. High volatile matter of coal leads to the estimation of low activation energy. It was observed that the activation energy under CO₂ atmosphere at 400-600°C is less as compared to N₂ inert atmosphere. At this temperature range, it is estimated that 15-23% reduction in the activation energy under CO₂ atmosphere. This shows the reactivity of CO₂ gas with higher hydrocarbons of the coal volatile matters. The reactivity of CO₂ with the volatile matter of coal might occur through dry reforming reaction in which CO₂ reacts with higher hydrocarbon, aromatics of the tar content. The observed trend of Ea in the temperature range of 150-200˚C and 400-600˚C is HAC > LAC-1 >LAC-2 in both N₂ and CO₂ atmosphere. At the temperature range of 850-1000˚C, higher activation energy is estimated when compared to those values in the temperature range of 400-600°C. Above 800°C, char gasification through Boudouard reaction progressed under CO₂ atmosphere. It was observed that 8-20 kJ/mol of activation energy is increased during char gasification above 800°C compared to volatile matter pyrolysis between the temperature ranges of 400-600°C. The overall activation energy of the coals in the temperature range of 30-1000˚C is higher in N₂ atmosphere than CO₂ atmosphere. It can be concluded that higher hydrocarbons such as tar effectively undergoes cracking and reforming reactions in presence of CO₂. Thus, CO₂ gas is beneficial for the production of high calorific value syngas using high ash Indian coals.

Keywords: clean coal technology, CO₂ gasification, activation energy, underground coal gasification

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Authors: R. Abdeldjebar, B. Labbaci, L. Lahmar, L. Missoum, B. Moudden

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Today to build durably means to build in such a way to create, to preserve in the world an acceptable environment where ecology, social and economic implications are in the center of future generations interest. To achieve this goal, we tried to employ local, durable, powerful ground materials which lead to limit pollution, to have long lifetime, and possibility of recycling or recovery. Using them in the most rational way makes construction technically perfect and put an end to cement invasion, since ground bricks are simple to implement and create a useful decoration, original and pleasant which enables to preserve the historical architectural heritage. This work concerns the study of environmental effects on stabilized bricks of compressed ground, traditionally manufactured containing traditional quicklime after extinction in water as a basic component which offers to brick mechanical resistance in conformity with the standards. Experimental results of compression and bending are exposed and are in conformity with the used standards.

Keywords: characterization, BTS, quicklime, dune sand, environment, durable

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Authors: Christtestimony Oluwafemi Jesumoroti, AbdulLateef Ashola Olanrewaju, Khor Soo Cheen

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The worth of buildings is known by the quality of the maintenance imbibe in them. Maintenance management being carried out in the hospitals has a direct impact on the performance of the hospital buildings, environment, and sustainable infrastructure, and as such, there is a need to give it adequate attention. The media and reports on hospital buildings maintenance management in Malaysia were not favorable. Hospital buildings in Malaysia need to have proper structure for maintenance management and sustainability as this will enhance the good infrastructure for users and the entire nation. The paper reports the preliminary results of the determinants of maintenance in hospital buildings. To achieve the aim of this research, a survey questionnaire was administered to the users of the hospital buildings. The findings of the study revealed that there are lack of maintenance standard, use of poor quality components and materials, Improper response time, Poor complaint reporting system. Hence, the influent of rework, thorough responsibilities of quality performance of hospital buildings, and others are the results of the investigations.

Keywords: sustainable infrastructure, optimum performance, implementation, key performance indicators, maintenance policies

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Authors: Busari Lasisi

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Literary works are often devalued to mere fictions and are left with no essence and contributions to history. The sub-structured rational delineating literary works from history is anchored on the aesthetic and flowery expressions that are therein embedded for artistic enrichment. This does not distance a literary work (from whichever genres it is drawn) reflecting the socio-economic, cultural and political cum religious perspectives of a given people and society. This is the very reason justifying the veracity that a writer does not anchor his writing outside of his society. He writes mirroring (his or a given society’s) events, places and duration of consciousness thereby making history evident. In the light of this reality, literary works are not just seen as fictions, imaginative and unrealistic pieces; for they are never unconnected to history. Thus, making authors of literary works historians and their works engrafted useful historical documents. Using the works of Ahmadou Korouma, a renown Ivorian writer, the praxis of this paper therefore in New Historicism approach postulates that literary works are underlying unexplored historic materials, and literature a jumelle to history.

Keywords: literature, history, New Historicism, authors

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Authors: Sohail Yasin, Massimo Curti, Nemeshwaree Behary, Giorgio Rovero

Abstract:

It is well-known that the presence of discarded textile products in municipal landfills poses environmental problems due to leaching of chemical products from the textile to the environment. Incineration of such textiles is considered to be an efficient way to produce energy and reduce environmental impacts of textile materials at their end-of life stage. However, the presence of flame retardant products on textiles would decrease the energy yield and emit toxic gases during incineration stage. While some non-durable flame retardants can be removed by wet treatments (e.g. washing), these substances pollute water and pose concerns towards environmental health. Our study shows that infrared radiation can be used efficiently to degrade flame retardant products on the textiles. This method is finalized to minimize the decrease in energy yield during the incineration or gasification processes of flame retardant cotton fabrics.

Keywords: degradation, flame retardant, infrared radiation, cotton, incineration

Procedia PDF Downloads 369

Authors: Mohamed E. Harb, Enas Moustafa, Shaker Ebrahim, Moataz Soliman

Abstract:

In this paper pressure detectors were synthesized and characterized using hybrid perovskite/PVDF composites as an active layer. Methylammonium lead iodide (MAPbI₃) was synthesized from methylammonium iodide (MAI) (CH₃NH₃I) and lead iodide (PbI₂). Composites of perovskite/PVDF using different weight ratio were prepared as the active material. PVDF with weights percentages of 6%, 8%, and 10% was used. All prepared materials were investigated by x-ray diffraction (XRD), Fourier transforms infrared spectrum (FTIR) and scanning electron microscopy (SEM). A Versastat 4 Potentiostat Galvanostat instrument was used to perform the current-voltage characteristics of the fabricated sensors. The pressure sensors exhibited a voltage increase with applying different forces. Also, the current-voltage characteristics (CV) showed different effects with applying forces. So, the results showed a good pressure sensing performance.

Keywords: perovskite semiconductor, hybrid perovskite, PVDF, Pressure sensing

Procedia PDF Downloads 211

Authors: Uttam Neupane, Narendra Budha, Subash Kumar Bhattarai

Abstract:

Material management is an essential part in construction project management. There are a number of material management problems in the Nepalese construction industry, which contribute to an inefficient material management system. Ineffective material management can cause waste of time and money thus increasing the problem of time and cost overrun. An assessment of material management system with gap and solution was carried out on 20 construction projects implemented by the Federal Level Project Implementation Unit (FPIU); Kaski district of Nepal. To improve the material management process, the respondents have provided possible solutions to overcome the gaps seen in the current material management process. The possible solutions are preparation of material schedule in line with the construction schedule for material requirement planning, verifications of material and locating of source, purchasing of the required material in advance before commencement of work, classifying the materials, and managing the inventory based on their usage value and eliminating and reduction in wastages during the overall material management process.

Keywords: material management, construction site, inventory, construction project

Procedia PDF Downloads 76

Authors: Zhandos Tauanov, Dhawal Shah, Grigorios Itskos, Vasileios Inglezakis

Abstract:

Removal of mercury (II) from aqueous phase is of utmost importance, as it is highly toxic and hazardous to the environment and human health. One way of removal of mercury (II) ions from aqueous solutions is by using adsorbents derived from coal fly ash (CFA), such as synthetic zeolites. In this work, we present the hydrothermal production of synthetic zeolites from CFA with conversion rate of 75%. In order to produce silver containing nanocomposites, synthetic zeolites are subsequently impregnated with various amounts of silver nanoparticles, from 0.2 to 2wt.%. All produced zeolites and parent materials are characterized by XRD, XRF, BET, SEM, and TEM to obtain morphological and microstructural data. Moreover, mercury (II) ions removal from aqueous solutions with initial concentration of 10 ppm is studied. According to results, zeolites and Ag-nanocomposites demonstrate much higher removal than parent CFA (up to 98%). In addition to this, we could observe a distinct adsorption behavior depending on the loading of Ag NPs in nanocomposites. A possible reaction mechanism for both zeolites and Ag-nanocomposites is discussed.

Keywords: coal fly ash, mercury (II) removal, nanocomposites, silver nanoparticles, synthetic zeolite

Procedia PDF Downloads 278

Authors: Mohsen Negmeddin

Abstract:

Throughout their history, ancient Egyptians had known several kinds and types of boats, which were made from two main kinds of materials, the local one, as the dried papyrus reeds and the local tree trunks, the imported one, as the boats which were made from Lebanon cedar tree trunks. A varied using of these boats, as the fish hunting small boats, the transportation and trade boats "Cargo Boats", as well as the ceremonial boats, and the warfare boats. The research is intending for the last one, the warfare boats and the river/maritime battles since the beginning of ancient Egyptian civilization at the pre-historic era up till the end of the second intermediate period, to reveal the kinds and types of those fighting ships before establishing the Egyptian navy at the beginning of the New Kingdome (1550-1770 B.C). Two methods will follow at this research, the mention of names and titles of these ships through the texts (ancient Egyptian language) resources, and the depiction of it at the scenes.

Keywords: the warfare boats, the maritime battles, the pre-historic era, the second intermediate period

Procedia PDF Downloads 280

Authors: M. Alsaadi, A. Erkliğ, M. Bulut

Abstract:

This paper experimentally investigates the flexural and tensile properties of the industrial wastes sewage sludge ash (SSA) and fly ash (FA), and conventional ceramic powder silicon carbide (SiC) filled polyester composites. Four weight fractions (5, 10, 15 and 20 wt%) for each micro filler were used for production of composites. Then, test samples were produced according to ASTM. The resulting degree of particle dispersion in the polymer matrix was visualized by using scanning electron microscope (SEM). Results from this study showed that the tensile strength increased up to its maximum value at filler content 5 wt% of SSA, FA and SiC. Flexural strength increased with addition of particulate filler up to its maximum value at filler content 5 wt% of SSA and FA while for SiC decreased for all weight fractions gradually. The addition of SSA, FA and SiC fillers resulted in increase of tensile and flexural modulus for all the particulate composites. Industrial waste SSA can be used as an additive with polymer to produce composite materials.

Keywords: particle-reinforcement, sewage sludge ash, polymer matrix composites, mechanical properties

Procedia PDF Downloads 374

Authors: Mohd Suhaizan Shamsuddin

Abstract:

Urbanization exacerbates the environment quality and pressures of matured urban trees' growth and development in changing environment. The growth of struggled matured urban tree-roots by spreading within the existences of infrastructures, resulting in large damage to the structured and declined growth. Many physiological growths declined or damages by the present and installations of infrastructures within and nearby root zone. Afford to remain both matured urban tree and infrastructures as a service provider causes damage and death, respectively. Inasmuch, spending more expenditure on fixing both or removing matured urban trees as risky to the future environment as the mitigation methods to reduce the problems are unconcerned. This paper aims to explain mitigation method practices of reducing the encountered problems of matured urban tree-roots settling and infrastructures while modified urban soil to sustain at an optimum level. Three categories capturing encountered conflicts growth of matured urban tree-roots growth within and nearby infrastructures by mitigating the problems of limited soil spaces, poor soil structures and soil space barrier installations and maintenance. The limited soil space encountered many conflicts and identified six methods that mitigate the survival tree-roots, such as soil volume/mounding, soil replacement/amendment for the radial trench, soil spacing-root bridge, root tunneling, walkway/pavement rising/diverted, and suspended pavement. The limited soil spaces are mitigation affords of inadequate soil-roots and spreading root settling and modification of construction soil media since the barrier existed and installed in root trails or zones. This is the reason for enabling tree-roots spreading and finds adequate sources (nutrients, water uptake and oxygen), spaces and functioning to stability stand of root anchorage since the matured tree grows larger. The poor soil structures were identified as three methods to mitigate soil materials' problems, and fewer soil voids comprise skeletal soil, structural soil, and soil cell. Mitigation of poor soil structure is altering the existing and introducing new structures by modifying the quantities and materials ratio allowing more voids beneath for roots spreading by considering the above structure of foot and vehicle traffics functioning or load-bearing. The soil space barrier installations and maintenance recognized to sustain both infrastructures and tree-roots grown in limited spaces and its benefits, the root barrier installations and root pruning are recommended. In conclusion, these recommended methods attempt to mitigate the present problems encountered at a particular place and problems among tree-roots and infrastructures exist. The combined method is the best way to alleviates the conflicts since the recognized conflicts are between tree-roots and man-made while the urban soil is modified. These presenting methods are most considered to sustain the matured urban trees' lifespan growth in the urban environment.

Keywords: urban tree-roots, limited soil spaces, poor soil structures, soil space barrier and maintenance

Procedia PDF Downloads 203