Search results for: thermal reliability

Authors: C. Benhamideche

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Fluoroaluminate glasses have been reported as the earliest heavy metal fluoride glasses. By comparison with flurozirconate glasses, they offer a set of similar optical features, but also some differences in their elastic and chemical properties. In practice they have been less developed because their stability against devitrification is smaller than that of the most stable fluoroziconates. The purpose of this study was to investigate glass formation in systems AlF3-YF3-PbF2-MgF2-MF2 (M= Li, Na, K). Synthesis was implemented at room atmosphere using the ammonium fluoride processing. After fining, the liquid was into a preheated brass mold, then annealed below the glass transition temperature for several hours. The samples were polished for optical measurements. Glass formation has been investigated in a systematic way, using pseudo ternary systems in order to allow parameters to vary at the same time. We have chosen the most stable glass compositions for the determination of the physical properties. These properties including characteristic temperatures, density and proprieties elastic. Glass stability increases in multicomponent glasses. Bulk samples have been prepared for physical characterization. These glasses have a potential interest for passive optical fibers because they are less sensitive to water attack than ZBLAN glass, mechanically stronger. It is expected they could have a larger damage threshold for laser power transmission.

Keywords: fluoride glass, aluminium fluoride, thermal properties, density, proprieties elastic

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Authors: Golshid Gilani, Albert De La Fuente, Ana Blanco

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Sustainability assessment of new and existing buildings has generated a growing interest due to the evident environmental, social and economic impacts during their construction and service life. Façades, as one of the most important exterior elements of a building, may contribute to the building sustainability by reducing the amount of energy consumption and providing thermal comfort for the inhabitants, thus minimizing the environmental impact on both the building and on the environment. Various methods have been used for the sustainability assessment of buildings due to the importance of this issue. However, most of the existing methods mainly concentrate on environmental and economic aspects, disregarding the third pillar of sustainability, which is the social aspect. Besides, there is a little focus on comprehensive sustainability assessment of facades, as an important element of a building. This confirms the need of developing methods for assessing the sustainable performance of building façades as an important step in achieving building sustainability. In this respect, this paper aims at presenting a model for assessing the global sustainability of façade systems. for that purpose, the Integrated Value Model for Sustainable Assessment (MIVES), a Multi-Criteria Decision Making model that integrates the main sustainability requirements (economic, environmental and social) and includes the concept of value functions, used as an assessment tool.

Keywords: façade, MCDM, MIVES, sustainability

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Authors: Buse A. Ataç, Doğan K. Cenan, Arda Çetinkaya, Naz D. Şahin, Köksal Sanlı, Zeynep Koç, Akın Kısa

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With its spatial data reliability, interpretation and questioning capabilities, Geographical Information Systems make significant contributions to scientists, planners and practitioners. Geographic information systems have received great attention in today's digital world, growing rapidly, and increasing the efficiency of use. Access to and use of current and accurate geographical data, which are the most important components of the Geographical Information System, has become a necessity rather than a need for sustainable and economic development. This project aims to enable sharing of data collected by public institutions and organizations on a web-based platform. Within the scope of the project, INSPIRE (Infrastructure for Spatial Information in the European Community) data specifications are considered as a road-map. In this context, Turkey's National Geographic Information System (TUCBS) Integration Project supports sharing spatial data within 61 pilot public institutions as complied with defined national standards. In this paper, which is prepared by the project team members in the TUCBS Integration Project, the technical process with a detailed methodology is explained. In this context, the main technical processes of the Project consist of Geographic Data Analysis, Geographic Data Harmonization (Standardization), Web Service Creation (WMS, WFS) and Metadata Creation-Publication. In this paper, the integration process carried out to provide the data produced by 61 institutions to be shared from the National Geographic Data Portal (GEOPORTAL), have been trying to be conveyed with a detailed methodology.

Keywords: data specification, geoportal, GIS, INSPIRE, Turkish National Geographic Information System, TUCBS, Turkey's national geographic information system

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Authors: Tytus Tulwin, Ksenia Siadkowska, Rafał Sochaczewski

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A high power radial reciprocating engine is characterized by a large displacement volume of a combustion chamber. Choosing the right moment for ignition is important for a high performance or high reliability and ignition certainty. This work shows methods of simulating ignition process and its impact on engine parameters. For given conditions a flame speed is limited when a deflagration combustion takes place. Therefore, a larger length scale of the combustion chamber compared to a standard size automotive engine makes combustion take longer time to propagate. In order to speed up the mixture burn-up time the second spark is introduced. The transient Computational Fluid Dynamics model capable of simulating multicycle engine processes was developed. The CFD model consists of ECFM-3Z combustion and species transport models. A relative ignition timing difference for the both spark sources is constant. The temperature distribution on engine walls was calculated in the separate conjugate heat transfer simulation. The in-cylinder pressure validation was performed for take-off power flight conditions. The influence of ignition timing on parameters like in-cylinder temperature or rate of heat release was analyzed. The most advantageous spark timing for the highest power output was chosen. The conditions around the spark plug locations for the pre-ignition period were analyzed. 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

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Authors: Rehan Waheed, Hasan Aftab Saeed, Wasim Tarar, Khalid Mahmood, Sajid Ullah Butt

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Electromagnetic Interference (EMI) shielded doors made from brass extruded channels need to be welded with shielded enclosures to attain optimum shielding performance. Control of welding induced distortion is a problem in welding dissimilar metals like steel and brass. In this research, soldering of the steel-brass joint has been proposed to avoid weld distortion. The material used for brass channel is UNS C36000. The thickness of brass is defined by the manufacturing process, i.e. extrusion. The thickness of shielded enclosure material (ASTM A36) can be varied to produce joint between the dissimilar metals. Steel sections of different gauges are soldered using (91% tin, 9% zinc) solder to the brass, and strength of joint is measured by standard test procedures. It is observed that thin steel sheets produce a stronger bond with brass. The steel sections further require to be welded with shielded enclosure steel sheets through TIG welding process. Stresses and deformation in the vicinity of soldered portion is calculated through FE simulation. Crack formation in soldered area is also studied through experimental work. It has been found that in thin sheets deformation produced due to applied force is localized and has no effect on soldered joint area whereas in thick sheets profound cracks have been observed in soldered joint. The shielding effectiveness of EMI shielded door is compromised due to these cracks. The shielding effectiveness of the specimens is tested and results are compared.

Keywords: dissimilar metal, EMI shielding, joint strength, soldering

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Authors: O. Afshar

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A solar receiver is designed for operation under extremely uneven heat flux distribution, cyclic weather, and cloud transient cycle conditions, which can include large thermal stress and even receiver failure. In this study, the effect of different oil velocity on convection coefficient factor and impact of wind velocity on local Nusselt number by Finite Volume Method will be analyzed. This study is organized to give an overview of the numerical modeling using a MATLAB software, as an accurate, time efficient and economical way of analyzing the heat transfer trends over stationary receiver tube for different Reynolds number. The results reveal when oil velocity is below 0.33m/s, the value of convection coefficient is negligible at low temperature. The numerical graphs indicate that when oil velocity increases up to 1.2 m/s, heat convection coefficient increases significantly. In fact, a reduction in oil velocity causes a reduction in heat conduction through the glass envelope. In addition, the different local Nusselt number is reduced when the wind blows toward the concave side of the collector and it has a significant effect on heat losses reduction through the glass envelope.

Keywords: receiver tube, heat convection, heat conduction, Nusselt number

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Authors: Ramy Kamel Fekrey Gadelrab

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Textile sensors have gained a lot of interest in recent years as it is instrumental in monitoring physiological and environmental changes, for a better diagnosis that can be useful in various fields like medical textiles, sports textiles, protective textiles, agro textiles, and geo-textiles. Moreover, with the development of flexible textile-based wearable sensors, the functionality of smart clothing is augmented for a more improved user experience when it comes to technical textiles. In this context, conductive textiles using new composites and nanomaterials are being developed while considering its compatibility with the textile manufacturing processes. This review aims to provide a comprehensive and detailed overview of the contemporary advancements in textile-based wearable physical sensors, used in the field of medical, security, surveillance, and protection, from a global perspective. The methodology used is through analysing various examples of integration of wearable textile-based sensors with clothing for daily use, keeping in mind the technological advances in the same. By comparing various case studies, it come across various challenges textile sensors, in terms of stability, the comfort of movement, and reliable sensing components to enable accurate measurements, in spite of progress in the engineering of the wearable. Addressing such concerns is critical for the future success of wearable sensors.

Keywords: nanoparticles, enzymes, immobilization, textilesconductive yarn, e-textiles, smart textiles, thermal analysisflexible textile-based wearable sensors, contemporary advancements, conductive textiles, body conformal design

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Authors: Helena M. Wilhelm, Paulo O. Fernandes, Laís P. Dill, Kethlyn G. Moscon

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The use of vegetable oil (or natural ester) as an insulating fluid in electrical transformers is a trend that aims to contribute to environmental preservation since it is biodegradable and non-toxic. Besides, vegetable oil has high flash and combustion points, being considered a fire safety fluid. However, vegetable oil is usually less stable towards oxidation than mineral oil. Both insulating fluids, mineral and vegetable oils, need to be tested periodically according to specific standards. Oxidation stability can be determined by the induction period measured by conductivity method (Rancimat) by monitoring the effectivity of oil’s antioxidant additives, a methodology already developed for food application and biodiesel but still not standardized for insulating fluids. Besides adequate oxidation stability, fluids must be compatible with transformer's construction materials under normal operating conditions to ensure that damage to the oil and parts of the transformer does not occur. ASTM standard and Brazilian normative differ in parameters evaluated, which reveals the need to regulate tests for each oil type. The aim of this study was to assess oxidation stability and compatibility of vegetable oils to suggest the best way to assure a viable performance of vegetable oil as transformer insulating fluid. The determination of the induction period for several vegetable insulating oils from the local market by using Rancimat was carried out according to BS EN 14112 standard, at different temperatures (110, 120, and 130 °C). Also, the compatibility of vegetable oil was assessed according to ASTM and ABNT NBR standards. The main results showed that the best temperature for use in the Rancimat test is 130 °C, which allows a better observation of conductivity change. The compatibility test results presented differences between vegetable and mineral oil standards that should be taken into account in oil testing since materials compatibility and oxidation stability are essential for equipment reliability.

Keywords: compatibility, Rancimat, natural ester, vegetable oil

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Authors: Mohammad Reza Zamanian

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The construction industry has always been recognized as one of the most dangerous available industries, and the statistics of accidents and injuries resulting from it say that the safety category needs more attention and the arrival of up-to-date technologies in this field. Building information modeling (BIM) is one of the relatively new and applicable technologies in Iran, that the necessity of using it is increasingly evident. The main purposes of this research are to evaluate the feasibility of using this technology in the safety sector of construction projects and to evaluate the effectiveness and operationality of its various applications in this sector. These applications were collected and categorized after reviewing past studies and researches then a questionnaire based on Delphi method criteria was presented to 30 experts who were thoroughly familiar with modeling software and safety guidelines. After receiving and exporting the answers to SPSS software, the validity and reliability of the questionnaire were assessed to evaluate the measuring tools. Fuzzy logic is a good way to analyze data because of its flexibility in dealing with ambiguity and uncertainty issues, and the implementation of the Delphi method in the fuzzy environment overcomes the uncertainties in decision making. Therefore, this method was used for data analysis, and the results indicate the usefulness and effectiveness of BIM in projects and improvement of safety status at different stages of construction. Finally, the applications and the sections discussed were ranked in order of priority for efficiency and effectiveness. Safety planning is considered as the most influential part of the safety of BIM among the four sectors discussed, and planning for the installation of protective fences and barriers to prevent falls and site layout planning with a safety approach based on a 3D model are the most important applications of BIM among the 18 applications to improve the safety of construction projects.

Keywords: building information modeling, safety of construction projects, Delphi method, fuzzy logic

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Authors: Shih-Heng Sun, Hsiu-Yu Chang

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“Family centered service model” becomes mainstream in early intervention. Family outcome should be evaluated in addition child improvement in terms of outcome evaluation in early intervention. The purpose of this study is to develop a surveys to evaluate family outcomes in early intervention. Method: “Family Outcomes Survey- Revised Taiwan Version” (FOS-RT) was developed through translation, back-translation, and review by the original author. Expert meeting was held to determine the content validity. Two hundred and eighty six parent-child dyads recruited from 10 local Early Intervention Resource Centers (EIRC) participated in the study after they signed inform consent. The results showed both parts of FOS-RT exhibits good internal consistency and test-retest reliability. The result of confirmatory factor analysis indicated moderate fit of 5 factor structure of part A and 3 factor structure of part B of FOS-RT. The correlation between different sessions reached moderate to high level reveals some sessions measure similar latent trait of family outcomes. Correlation between FOS-RT and Parents‘ Perceived Parenting Skills Questionnaire was calculated to determine the convergence validity. The moderate correlation indicates the two assessments measure different parts of early intervention outcome although both assessments have similar sub-scales. The results of this study support FOS-RT is a valid and reliable tool to evaluate family outcome after the family and children with developmental disability receive early intervention services.

Keywords: early intervention, family service, outcome evaluation, parenting skills, family centered

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Authors: Tünde Tifordiána Simonyi, Tímea Harmath-Tánczos

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The primary aim of the current research is to present the significance of a multicultural perspective in clinical neuropsychology and to present the test battery of the Multicultural Neuropsychological Scale (MUNS). The method includes the MUNS screening tool that involves stimuli common to most cultures in the world. The test battery measures general cognitive functioning focusing on five cognitive domains (memory, executive function, language, visual construction, and attention) tested with seven subtests that can be utilized within a wide age range (15-89), and lower and higher education participants. It is a scale that is sensitive to mild cognitive impairments. Our study presents the first results with the Hungarian translation of MUNS on a healthy sample. The education range was 4-25 years of schooling. The Hungarian sample was recruited by snowball sampling. Within the investigated population (N=151) the age curve follows an inverted U-shaped curve regarding cognitive performance with a high load on memory. Age, reading fluency, and years of education significantly influenced test scores. The sample was tested twice within a 14-49 days interval to determine test-retest reliability, which is satisfactory. Besides the findings of the study and the introduction of the test battery, the article also highlights its potential benefits for both research and clinical neuropsychological practice. The importance of adapting, validating and standardizing the test in other languages besides the Hungarian language context is also stressed. This test battery could serve as a helpful tool in mapping general cognitive functions in psychiatric and neurological disorders regardless of the cultural background of the patients.

Keywords: general cognitive functioning, multicultural, MUNS, neuropsychological test battery

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Authors: Ammar Alobaidy, Lamees Alsawafi, Malak Almawali, Balqees Alabri, Hajer Alhamrashdi

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Background: There is scarce data in the literature concerning the use of Arabic version neuron psychological cognitive tests in the geriatric age group of the Omani population. Objectives: Our aim is to obtain norms for normal elderly Omanis assessed by The Consortium to Establish a Registry for Alzheimer's disease (CERAD) neuro psychological battery and to compare these norms with other studies in the literature. Methods: 84 attendants and visitors of in-patients at Sultan Qaboos University Hospital, elder than 55 years, were interviewed. All participants were assessed by Dementia Rating Scale & Geriatric Depression Scale to ensure the integrity of their activities of daily living and the absence of depression, respectively. The performance of all participants in the CERAD battery was rated by a single rater to optimize the inter-rater reliability. Results: The cut-point for average performance in CERAD battery is dependent on the age, sex, and level of education and cannot be set as a single cut-point for all elderly Omanis. Conclusion: This study has shown the effect of age, sex, and level of education on the cognitive performance of normal elderly Omanis. The normative data obtained from this study can be utilized to differentiate between the cognitive decline of normal aging and the cognitive impairment due to various neuro cognitive disorders in the elderly Omanis, and probably culturally similar Arabic speaking communities.

Keywords: CERAD, neuropsychological battery, normal aging, elderly Omanis

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Authors: Shruti Sakarkar, Jega Jegatheesan, Srinivasan Madapusi

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Photocatalytic membranes have shown great potential for the removal of an organic and inorganic pollutant from wastewater as it combines the degradation and antibacterial properties from photocatalysis and physical separation by the membrane in a single unit. Incorporation of the semiconductor in membrane structure results in enhancing the performance and the properties of the membrane. In this study porous ultrafiltration polyvinylidene fluoride (PVDF) membranes with entrapped TiO₂ nanoparticle were prepared by phase inversion method and further used for the degradation of reactive orange 16 (RO16). Prepared photocatalytic membranes were characterized by the scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), contact angle, and atomic force microscope (AFM). The addition of TiO₂ nanopartparticles improves the strength and thermal stability of the membrane. In particular hydrophilicity and permeability increases with the increase of TiO₂ nanoparticles into the membrane. The photocatalytic membrane achieves 80-85% degrdation of RO16. The impact of different parameters such as pH, concentration of photocatalyst, dye concentration and effect of H₂O₂ were analysed. The best conditions for dye degradation were an initial dye concentration of 50 mg/L, with a membrane containing TiO₂ loading of 2wt%. It was observed that in the presence of H₂O₂, degradation increases with increasing H₂O₂ concentration and reached up to 95-98%. The high quality permeates obtained from the photocatalytic membrane can be reused.

Keywords: photocatalytic membrane, TiO₂, PVDF, nanoparticles

Procedia PDF Downloads 158

Authors: Thamo Sutharssan, Diogo Montalvao, Wen-Chung Wang, Yong Chen, Claudia Pisac

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A combined heat and power (CHP) system is an efficient and clean way to generate power (electricity). Heat produced by the CHP system can be used for water and space heating. The CHP system which uses hydrogen as fuel produces zero carbon emission. Its’ efficiency can reach more than 80% whereas that of a traditional power station can only reach up to 50% because much of the thermal energy is wasted. The other advantages of CHP systems include that they can decentralize energy generation, improve energy security and sustainability, and significantly reduce the energy cost to the users. This paper presents the economic benefits of using a CHP system in the domestic environment. For this analysis, natural gas is considered as potential fuel as the hydrogen fuel cell based CHP systems are rarely used. UK government incentives for CHP systems are also considered as the added benefit. Results show that CHP requires a significant initial investment in return it can reduce the annual energy bill significantly. Results show that an investment may be paid back in 7 years. After the back period, CHP can run for about 3 years as most of the CHP manufacturers provide 10-year warranty.

Keywords: combined heat and power, clean energy, hydrogen fuel cell, economic analysis of CHP, zero emission

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Authors: Mohamed M. Emara, Heba Ashraf

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This study is to investigation the effect of silicon carbide (SiC) particle size and thermo-mechanical processing on dimensional stability of aluminum alloy 2124. Three combinations of SiC weight fractions are investigated, 2.5, 5, and 10 wt. % with different SiC particle sizes (25 μm, 5 μm, and 100nm) were produced using mechanical ball mill. The standard testing samples were fabricated using powder metallurgy technique. Both samples, prior and after extrusion, were heated from room temperature up to 400ºC in a dilatometer at different heating rates, that is, 10, 20, and 40ºC/min. The analysis showed that for all materials, there was an increase in length change as temperature increased and the temperature sensitivity of aluminum alloy decreased in the presence of both micro and nano-sized silicon carbide. For all conditions, nanocomposites showed better dimensional stability compared to conventional Al 2124/SiC composites. The after extrusion samples showed better thermal stability and less temperature sensitivity for the aluminum alloy for both micro and nano-sized silicon carbide.

Keywords: aluminum 2124 metal matrix composite, SiC nano-sized reinforcements, powder metallurgy, extrusion mechanical ball mill, dimensional stability

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Authors: Rosa Christodoulaki, Irene Koronaki, Panagiotis Tsekouras

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The aim of this study is to analyze the energy performance of a spherical Stationary Reflector / Tracking Absorber (SRTA) solar concentrator. This type of collector consists of a segment of a spherical mirror placed in a stationary position facing the sun and a cylindrical absorber that tracks the sun by a simple pivoting motion about the center of curvature of the reflector. The energy analysis is performed through the development of a dynamic simulation model in TRNSYS software that calculates the annual heat production and the efficiency of the SRTA solar concentrator. The effect of solar concentrator design features and characteristics, such the reflector material, the reflector diameter, the receiver type, the solar radiation level and the concentration ratio, are discussed in details. Moreover, the energy performance curve of the SRTA solar concentrator, for various temperature differences between the mean fluid temperature and the ambient temperature and radiation intensities is drawn. The results are shown in diagrams, visualizing the effect of solar, optical and thermal parameters to the overall performance of the SRTA solar concentrator throughout the year. The analysis indicates that the SRTA solar concentrator can operate efficiently under a wide range of operating conditions.

Keywords: concentrating solar collector, energy analysis , stationary reflector, tracking absorber

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Authors: Yasir Ali Arfat

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Composite films based on fish protein isolate (FPI) and fish skin gelatin (FSG) blend incorporated with 50 and 100% (w/w, protein) basil leaf essential oil (BEO) in the absence and presence of 3% (w/w, protein) ZnO nanoparticles (ZnONP) were prepared and characterised. Tensile strength (TS) decreased, whilst elongation at break (EAB) increased as BEO level increased (p < 0.05). However, ZnONP addition resulted in higher TS but lower EAB (p < 0.05). The lowest water vapour permeability (WVP) was observed for the film incorporated with 100% BEO and 3% ZnONP (p < 0.05). BEO and ZnONP incorporation decreased transparency of FPI/FSG films (p < 0.05). FTIR spectra indicated that films added with BEO exhibited higher hydrophobicity. Both BEO and ZnONP had a marked impact on thermal stability of the films. Microstructural study revealed that presence of ZnONP prevented bilayer formation of film containing 100% BEO. FPI/FSG films incorporated with 100% BEO, especially in combination with ZnONP, exhibited strong antibacterial activity against food pathogenic and spoilage bacteria and thus could be used as an active food packaging material to ensure safety and to extend the shelf-life of packaged foods.

Keywords: bionanocomposite, fish protein isolate, fish skin gelatin, basil essential oil, ZnO nanoparticles, antimicrobial packaging

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Authors: Donald B. Enu, Clement O. Ukpor, Abigail E. Okon

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Unreliable scoring of students’ performance by lecturers short-chains students’ assessment in terms of underequipping the school authority with facts as intended by society through the curriculum hence, the learners, the school and the society are cheated because the usefulness of testing is defeated. This study, therefore, examined lecturers’ scoring objectivity of essay items in the Department of Social Science Education, University of Calabar, Nigeria. Specifically, it assessed lecturers’ perception of the relevance of scoring rubrics and its level of application. Data were collected from all the 36 lecturers in the Department (28 members and 8 non-members adjourned to the department), through a 20-item questionnaire and checklist instruments. A case-study design was adopted. Descriptive statistics of frequency counts, weighted means, standard deviations, and percentages were used to analyze data gathered. A mean score of 2.5 and or 60 percent and above formed the acceptance or significant level in decision taking. It was found that lecturers perceived the use of scoring rubrics as a relevant practice to ensure fairness and reliable treatment of examiners scripts particularly in marking essay items and that there is a moderately high level of adherence to the application of scoring rubrics. It was also observed that some criteria necessary for the scoring objectivity of essay items were not fully put in place in the department. It was recommended strongly that students’ identities be hidden while marking and that pre-determined marking scheme should be prepared centrally and strictly adhered to during marking and recording of scores. Conference marking should be enforced in the department.

Keywords: essay items, objective scoring, scorers reliability, scoring rubrics

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Authors: Shane D. Inder, Mehrdad Khamooshi

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Efficient energy storage is a crucial factor in facilitating the uptake of renewable energy resources. Among the many options available for energy storage systems required to balance imbalanced supply and demand cycles, compressed air energy storage (CAES) is a proven technology in grid-scale applications. This paper reviews the current state of micro scale CAES technology and describes a micro-scale advanced adiabatic CAES (A-CAES) system, where heat generated during compression is stored for use in the discharge phase. It will also describe a thermodynamic model, developed in EES (Engineering Equation Solver) to evaluate the performance and critical parameters of the discharge phase of the proposed system. Three configurations are explained including: single turbine without preheater, two turbines with preheaters, and three turbines with preheaters. It is shown that the micro-scale A-CAES is highly dependent upon key parameters including; regulator pressure, air pressure and volume, thermal energy storage temperature and flow rate and the number of turbines. It was found that a micro-scale AA-CAES, when optimized with an appropriate configuration, could deliver energy input to output efficiency of up to 70%.

Keywords: CAES, adiabatic compressed air energy storage, expansion phase, micro generation, thermodynamic

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Authors: Vaishali D. Khairnar

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The main aim is to provide lower-latency and highly reliable communication facilities for vehicles in the automobile industry; vehicle-to-everything (V2X) communication basically intends to increase expressway road security and its effectiveness. The Ultra-Reliable Low-Latency Communications (URLLC) algorithm and cellular networks are applied in combination with Mobile Broadband (MBB). This is particularly used in express way safety-based driving applications. Expressway vehicle drivers (humans) will communicate in V2X systems using the sixth-generation (6G) communication systems which have very high-speed mobility features. As a result, we need to determine how to ensure reliable and consistent wireless communication links and improve the quality to increase channel gain, which is becoming a challenge that needs to be addressed. To overcome this challenge, we proposed a unique multi-user scheduling algorithm for ultra-massive multiple-input multiple-output (MIMO) systems using 6G. In wideband wireless network access in case of high traffic and also in medium traffic conditions, moreover offering quality-of-service (QoS) to distinct service groups with synchronized contemporaneous traffic on the highway like the Mumbai-Pune expressway becomes a critical problem. Opportunist MAC (OMAC) is a way of proposing communication across a wireless communication link that can change in space and time and might overcome the above-mentioned challenge. Therefore, a multi-user scheduling algorithm is proposed for MIMO systems using a cross-layered MAC protocol to achieve URLLC and high reliability in V2X communication.

Keywords: ultra-reliable low latency communications, vehicle-to-everything communication, multiple-input multiple-output systems, multi-user scheduling algorithm

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Authors: Mitra Sadoughi

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This study presents the knowledge-sharing model based on individual and organizational factors related to faculty members. To achieve this goal, individual and organizational factors were presented through qualitative research in the form of open codes, axial, and selective observations; then, the final model was obtained using structural equation model. Participants included 1,719 faculty members of the Azad Universities, Mazandaran Province, Region 3. The samples related to the qualitative survey included 25 faculty members experienced at teaching and the samples related to the quantitative survey included 326 faculty members selected by multistage cluster sampling. A 72-item questionnaire was used to measure the quantitative variables. The reliability of the questionnaire was 0.93. Its content and face validity was determined with the help of faculty members, consultants, and other experts. For the analysis of quantitative data obtained from structural model and regression, SPSS and LISREL were used. The results showed that the status of knowledge sharing is moderate in the universities. Individual factors influencing knowledge sharing included the sharing of educational materials, perception, confidence and knowledge self-efficiency, and organizational factors influencing knowledge sharing included structural social capital, cognitive social capital, social capital relations, organizational communication, organizational structure, organizational culture, IT infrastructure and systems of rewards. Finally, it was found that the contribution of individual factors on knowledge sharing was more than organizational factors; therefore, a model was presented in which contribution of individual and organizational factors were determined.

Keywords: knowledge sharing, social capital, organizational communication, knowledge self-efficiency, perception, trust, organizational culture

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Authors: Jae-Yong Park, Gwancheol Seo, Young-Ho Kim

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Microvoids, sometimes called Kikendall voids, generally form in the interfaces between Sn-based solders and Cu and degrade the mechanical and electrical properties of the solder joints. The microvoid formation is known as the rapid interdiffusion between Sn and Cu and impurity content in the Cu. Cu electroplating from the acid solutions has been widely used by microelectronic packaging industry for both printed circuit board (PCB) and integrated circuit (IC) applications. The quality of electroplated Cu that can be optimized by the electroplating conditions is critical for the solder joint reliability. In this paper, the influence of electroplating conditions on the microvoid growth in the interfaces between Sn-3.0Ag-0.5Cu (SAC) solder and Cu layer was investigated during isothermal aging. The Cu layers were electroplated by controlling the additive of electroplating bath and current density to induce various microvoid densities. The electroplating bath consisted of sulfate, sulfuric acid, and additives and the current density of 5-15 mA/cm2 for each bath was used. After aging at 180 °C for up to 250 h, typical bi-layer of Cu6Sn5 and Cu3Sn intermetallic compounds (IMCs) was gradually growth at the SAC/Cu interface and microvoid density in the Cu3Sn showed disparities in the electroplating conditions. As the current density increased, the microvoid formation was accelerated in all electroplating baths. The higher current density induced, the higher impurity content in the electroplated Cu. When the polyethylene glycol (PEG) and Cl- ion were mixed in an electroplating bath, the microvoid formation was the highest compared to other electroplating baths. On the other hand, the overall IMC thickness was similar in all samples irrespective of the electroplating conditions. Impurity content in electroplated Cu influenced the microvoid growth, but the IMC growth was not affected by the impurity content. In conclusion, the electroplated conditions are properly optimized to avoid the excessive microvoid formation that results in brittle fracture of solder joint under high strain rate loading.

Keywords: electroplating, additive, microvoid, intermetallic compound

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Authors: Usman Tunde Saadu, Adedayo Adesokan, Raseed Adewale Hamsat

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This study examined the influence of procrastination on the academic achievement of students in tertiary institutions in Kwara State, Nigeria. Descriptive survey was adopted for this study and the total number of 300 respondents participated in the study. Stratified and simple random sampling techniques were used to select 3 institutions and 30 departments respectively. Systematic sampling technique was used to select 10 final year students in each department. Two instruments were used to obtain data from the respondents. Procrastination Assessment Scale adapted from Solomon and Rothblum (1984) and a proforma designed by researchers to obtain students CGPA in 2013/2014 academic session. The reliability score of 0.80 was obtained for the instrument using split half method. One research question and one hypothesis were postulated for this study. Percentage was employed to answer research question while research hypothesis was tested with t-test statistical analysis at 0.05 level of significant. The findings of this study revealed that most of final year students in tertiary institutions in Kwara State procrastinated because 82.3% engaged in procrastination while 17.7% did not procrastinate. Also, the study revealed that there was a significant difference between the academic achievement of tertiary institution students who procrastinate and those who did not procrastinate (cal. t-value =2.634 < critical t-value = 1.960). Students who did not engage in act of procrastinate achieved better academically than students who engage in procrastination. Based on the findings of this study, the following recommendations were made; procrastination as a concept, should be taught at the various institutions so that students will understand what the concept is all about. Guidance and counsellor and educational psychologists should be employed at various institutions to handle students who procrastinate so that appropriate methods will be recommended so solve the problem.

Keywords: academic, achievement, procrastination, institution

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Authors: Yusuf Kaygısız, Necmetti̇n Maraşlı

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Aluminum alloys are produced and used at various areas of industry and especially in the aerospace industry. The advantages of these alloys over traditional iron-based alloys are lightweight, corrosion resistance, and very good thermal and electrical conductivity. The aim of this work is to experimentally investigate the effect of growth rates on the eutectic spacings (λ), microhardness, tensile strength and electrical resistivity in Al–30wt.%Cu–6wt.%Mg eutectic alloy. Al–Cu–Mg eutectic alloy was directionally solidified at a constant temperature gradient (G=8.55 K/mm) with different growth rates, 9.43 to 173.3 µm/s by using a Bridgman-type furnace. The dependency of microstructure, microhardness, tensile strength and electrical resistivity for directionally solidified the Al-Cu-Mg eutectic alloy were investigated. Eutectic microstructure is consisting of regular Al2CuMg lamellar and Al2Cu rod phases with in the α (Al) solid solution matrix. The lamellar eutectic spacings were measured from transverse sections of the samples. It was found that the value of microstructures decrease with the increase the value the growth rates. The microhardness, tensile strength and electrical resistivity of the alloy also were measured from sample and relationships between them were experimentally analyzed by using regression analysis. According to present results, values tensile strength and electrical resistivity increase with increasing growth rates.

Keywords: directional solidification, aluminum alloys, microstructure, electrical properties, hardness test

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Authors: Gurlal Singh, Rupinder Singh

Abstract:

The possible role of the engine brake is to convert a power-producing engine into a power-absorbing retarding mechanism. In this braking system, exhaust gas (EG) from the internal combustion (IC) engines is used to operate air brake in the automobiles. Airbrake is most used braking system in vehicles. In the proposed model, instead of air brake, EG is used to operate the brake lever and stored in a specially designed tank. This pressure of EG is used to operate the pneumatic cylinder and brake lever. Filters used to remove the impurities from the EG, then it is allowed to store in the tank. Pressure relief valve is used to achieve a specific pressure in the tank and helps to avoid further damage to the tank as well as in an engine. The petrol engine is used in the proposed EG braking system. The petrol engine is chosen initially because it produces less impurity in the exhaust than diesel engines. Moreover, exhaust brake system (EBS) for the Diesel engines is composed of gate valve, pneumatic cylinder and exhaust brake valve with the on-off solenoid. Exhaust brake valve which is core component of EBS should have characteristics such as high reliability and long life. In a diesel engine, there is butterfly valve in exhaust manifold connected with solenoid switch which is used to on and off the butterfly valve. When butterfly valve closed partially, then the pressure starts built up inside the exhaust manifold and cylinder that actually resist the movement of piston leads to crankshaft getting stops resulting stopping of the flywheel. It creates breaking effect in a diesel engine. The exhaust brake is a supplementary breaking system to the service brake. It is noted that exhaust brake increased 2-3 fold the life of service brake may be due to the creation of negative torque which retards the speed of the engine. More study may also be warranted for the best suitable design of exhaust brake in a diesel engine.

Keywords: exhaust gas, automobiles, solenoid, airbrake

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Authors: Watcharapong Yaowarat, Thanee Kaewthummanukul, Waruntorn Jongrungrotsakul

Abstract:

Noise-induced hearing loss, the most significant occupational and safety problem among the working population, can be effectively prevented through hearing protection devices (HPDs) use. This study aimed to examine whether the following factors, perceived benefits, perceived barriers, perceived self-efficacy, and interpersonal and situational influences about using hearing protection could predict HPD use among 132 qualified workers in production lines at Kaolin Mineral Dressing factories, Uttaradit and Lampang provinces. Data collection was undertaken from August to September 2020 according to the interview form developed by Yaruang et al. (2010), which was assured by a panel of experts and its reliability value was at an acceptable level. Data analysis was performed using logistic regression analysis. The results revealed that only the situational factor of using hearing protection could predict HPD use, which accounted for 21.80 percent of the total variance for HPD use. It was also found that the study sample who had a score for the situational factors on using hearing protection greater than or equal to the median was 4.16 times more likely to use HPDs than those who had lower median scores. (OR = 4.16, p < .05). The results, thus, indicate that organization policies addressing worker health along with enhancing a supportive environment for HPD use, in particular, the provision of various HPDs, are of great importance. Therefore, occupational health nurses and related health teams should enhance workers’ use of HPDs effectively through knowledge dissemination by adopting strategies appropriate to the workplace context leading to an achievement of worker health policy focusing on work safety.

Keywords: predicting factors, hearing protection device, factors predicting hearing protection device use, kaolin mineral dressing factories

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Authors: Dionisios Panagiotaras, Dimitrios Papoulis, Elias Stathatos

Abstract:

Microfibrous palygorskite and tubular halloysite clay mineral combined with nanocrystalline TiO2 are incorporating in the preparation of nanocomposite films on glass substrates via sol-gel route at 450 °C. The synthesis is employing nonionic surfactant molecule as pore directing agent along with acetic acid-based sol-gel route without addition of water molecules. Drying and thermal treatment of composite films ensure elimination of organic material lead to the formation of TiO2 nanoparticles homogeneously distributed on the palygorskite or halloysite surfaces. Nanocomposite films without cracks of active anatase crystal phase on palygorskite and halloysite surfaces are characterized by microscopy techniques, UV-Vis spectroscopy, and porosimetry methods in order to examine their structural properties. The composite palygorskite-TiO2 and halloysite-TiO2 films with variable quantities of palygorskite and halloysite were tested as photocatalysts in the photo-oxidation of Basic Blue 41 azo dye in water. These nanocomposite films proved to be most promising photocatalysts and highly effective to dye’s decoloration in spite of small amount of palygorskite -TiO2 or halloysite- TiO2 catalyst immobilized onto glass substrates mainly due to the high surface area and uniform distribution of TiO2 on clay minerals avoiding aggregation.

Keywords: halloysite, palygorskite, photocatalysis, titanium dioxide

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Authors: Aleksander Nawrat, Karol Jędrasiak, Artur Ryt, Dawid Sobel

Abstract:

The goal of the article is to present a novel Multimedia Firearms Training System. The system was developed in order to compensate for major problems of existing shooting training systems. The designed and implemented solution can be characterized by five major advantages: algorithm for automatic geometric calibration, algorithm of photometric recalibration, firearms hit point detection using thermal imaging camera, IR laser spot tracking algorithm for after action review analysis, and implementation of ballistics equations. The combination of the abovementioned advantages in a single multimedia firearms training system creates a comprehensive solution for detecting and tracking of the target point usable for shooting training systems and improving intervention tactics of uniformed services. The introduced algorithms of geometric and photometric recalibration allow the use of economically viable commercially available projectors for systems that require long and intensive use without most of the negative impacts on color mapping of existing multi-projector multimedia shooting range systems. The article presents the results of the developed algorithms and their application in real training systems.

Keywords: firearms shot detection, geometric recalibration, photometric recalibration, IR tracking algorithm, thermography, ballistics

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Authors: Jingjue Bao, Ye Li, Yujie Qi

Abstract:

The explosive growth of ride-hailing has reshaped residents' travel behavior and plays a crucial role in urban mobility within the built environment. Contributing to the research of the spatial variation of ride-hailing demand and its relationship to the built environment and socioeconomic factors, this study utilizes multi-source data from Haikou, China, to construct a Multi-scale Geographically Weighted Regression model (MGWR), considering spatial scale heterogeneity. The regression results showed that MGWR model was demonstrated superior interpretability and reliability with an improvement of 3.4% on R2 and from 4853 to 4787 on AIC, compared with Geographically Weighted Regression model (GWR). Furthermore, to precisely identify the surrounding environment of sampling point, DeepLabv3+ model is employed to segment street-level images. Features extracted from these images are incorporated as variables in the regression model, further enhancing its rationality and accuracy by 7.78% improvement on R2 compared with the MGWR model only considered region-level variables. By integrating multi-scale geospatial data and utilizing advanced computer vision techniques, this study provides a comprehensive understanding of the spatial dynamics between ride-hailing demand and the urban built environment. The insights gained from this research are expected to contribute significantly to urban transportation planning and policy making, as well as ride-hailing platforms, facilitating the development of more efficient and effective mobility solutions in modern cities.

Keywords: travel behavior, ride-hailing, spatial relationship, built environment, street-level image

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Authors: Catrin Morgan, Atholl Johnston

Abstract:

Creatine supplementation should theoretically increase total muscle creatine and so enhance the generation of intramuscular phosphocreatine and subsequent ATP formation. The use of creatine as a potential ergogenic aid in sport has been an area of significant scientific research for a number of years. However the effect of creatine supplementation and swimming performance is a relatively new area of research and is the subject of this review. In swimming creatine supplementation could help maintain maximal power output, aid recovery and increase lean body mass. After investigating the underlying theory and science behind creatine supplementation, a literature review was conducted to identify the best evidence looking at the effect of creatine supplementation on swimming performance. The search identified 27 potential studies, and of these 17 were selected for review. The studies were then categorised into single sprint performance, which involves swimming a short distance race, or repeated interval performance, which involves swimming a series of sprints with intervals of rest between them. None of the studies on the effect of creatine controlled for the multiple confounding factors associated with measurement of swimming performance. The sample size in the studies was limited and this reduced the reliability of the studies and introduced the possibility of bias. The studies reviewed provided insufficient evidence to determine if creatine supplementation is beneficial to swimming performance. However, what data there was supported the use of creatine supplementation in repeated interval swimming rather than in single sprint swimming. From a review of the studies, it was calculated on average, there was a 1.37% increase in swimming performance with the use of creatine for repeated intervals and a 0.86% increase in performance for single sprint. While this may seem minor, it should be remembered that swimming races are often won by much smaller margins. In the 2012 London Olympics the Men’s 100 metres freestyle race was won by a margin of only 0.01 of a second. Therefore any potential benefit could make a dramatic difference to the final outcome of the race. Overall more research is warranted before the benefits of creatine supplementation in swimming performance can be further clarified.

Keywords: creatine supplementation, repeated interval, single sprint, swimming performance

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