Search results for: high stake tests

Authors: Mehmet Alpaslan Köroğlu, Musa Hakan Arslan, Muslu Kazım Körez

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Basic objective of this study is to create a regression analysis method that can estimate the length of a plastic hinge which is an important design parameter, by making use of the outcomes of (lateral load-lateral displacement hysteretic curves) the experimental studies conducted for the reinforced square concrete columns. For this aim, 170 different square reinforced concrete column tests results have been collected from the existing literature. The parameters which are thought affecting the plastic hinge length such as cross-section properties, features of material used, axial loading level, confinement of the column, longitudinal reinforcement bars in the columns etc. have been obtained from these 170 different square reinforced concrete column tests. In the study, when determining the length of plastic hinge, using the experimental test results, a regression analysis have been separately tested and compared with each other. In addition, the outcome of mentioned methods on determination of plastic hinge length of the reinforced concrete columns has been compared to other methods available in the literature.

Keywords: columns, plastic hinge length, regression analysis, reinforced concrete

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Authors: L. Bouqbis, H.W. Koyro, M. C. Harrouni, S. Daoud, L. F. Z. Ainlhout, C. I. Kammann

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The application of biochar to soils is becoming more and more common. Its application which is generally reported to improve the physical, chemical, and biological properties of soils, has an indirect effect on soil health and increased crop yields. However, many of the previous results are highly variable and dependent mainly on the initial soil properties, biochar characteristics, and production conditions. In this study, two biochars which are biochar II (BC II) derived from a blend of paper sludge and wheat husks and biochar 005 (BC 005) derived from sewage sludge with a KCl additive, are used, and the physical and chemical properties of BC II are characterized. To determine the potential impact of salt stress and toxic and volatile substances, the second part of this study focused on the effect biochars have on germination of salad (Lactuca sativa L.), barley (Hordeum vulgare), and cress (Lepidium sativum) respectively. Our results indicate that Biochar II showed some unique properties compared to the soil, such as high EC, high content of K, Na, Mg, and low content of heavy metals. Concerning salad and barley germination test, no negative effect of BC II and BC 005 was observed. However, a negative effect of BC 005 at 8% level was revealed. The test of the effect of volatile substances on germination of cress revealed a positive effect of BC II, while a negative effect was observed for BC 005. Moreover, the water holding capacities of biochar-sand mixtures increased with increasing biochar application. Collectively, BC II could be safely used for agriculture and could provide the potential for a better plant growth.

Keywords: biochar, phytotoxic tests, seedlings growth, water holding capacity

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Authors: Adji Achmad Rinaldo Fernandes

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Path analysis tests the relationship between variables through cause and effect. Before conducting further tests on path analysis, the assumption of linearity must be met. If the shape of the relationship is not linear and the shape of the curve is unknown, then use a nonparametric approach, one of which is a truncated spline. The purpose of this study is to estimate the function and get the best model on the nonparametric truncated spline path of linear, quadratic, and cubic orders with 1 and 2-knot points and determine the significance of the best function estimator in modeling farmer loyalty through the jackknife resampling method. This study uses secondary data through questionnaires to farmers in Sumbawa Regency who use SP-36 subsidized fertilizer products as many as 100 respondents. Based on the results of the analysis, it is known that the best-truncated spline nonparametric path model is the quadratic order of 2 knots with a coefficient of determination of 85.50%; the significance of the best-truncated spline nonparametric path estimator shows that all exogenous variables have a significant effect on endogenous variables.

Keywords: nonparametric path analysis, farmer loyalty, jackknife resampling, truncated spline

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Authors: Taraneh Ashrafi Motlagh, Abdolrasoul Daneshjoo

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Background and Aim: Increased fatigue causes injuries; the purpose of this article was to investigate the angular displacement of the hip and knee joints in girls with patellofemoral syndrome. Materials and Methods: Thirty girls with an average age (age 28.73±1.83, height 168.49±5.59, weight 63.73±12.73) participated in this study in two groups of 15, experimental and control. The jet evaluation test was taken from the subjects' knee and thigh angle, and then these tests were repeated with the application of different inclines of the treadmill; the tests were examined in a neutral position and in a positive and negative slope of 5 degrees. The mean and standard deviation were used to describe the data, and the Shapirovik test was used for the normalization of the data to compare and examine the variables in the two research groups using an independent t-test and repeated analysis of variance at a significance level of 0.05. Conclusion: In general, according to the current studies of people with patellofemoral syndrome, running on steep inclines, as well as running on a treadmill and making the incline angle of the treadmill within the limit of minus 5% to plus 5%, does not affect the improvement of this condition, and it is not recommended. And according to the research, girls with patellofemoral syndrome should be placed on the treadmill at an inclined angle to run.

Keywords: patellofemoral syndrome, angular displacement of the knee, angular displacement of the thigh

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Authors: Santhosh Ravichandran, F. J. Rodríguez-Varela

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In this study, a biocarbon (BC) was made from sewage sludge from the water treatment plant (PTAR) in Saltillo, Coahuila, Mexico. The sludge was carbonized in water and then chemically activated by pyrolysis. The biocarbon was evaluated physicochemically using XRD, SEM-EDS, and FESEM. A broad (002) peak attributable to graphitic structures indicates that the material is amorphous. The resultant biocarbon has a high specific surface area (412 m2 g-1), a large pore volume (0.39 cm3 g-1), interconnected hierarchical porosity, and outstanding electrochemical performance. It is appropriate for high-performance supercapacitor electrode materials due to its high specific capacitance of 358 F g-1, great rate capability, and outstanding cycling stability (around 87% capacitance retention after 10,000 cycles, even at a high current density of 19 A g-1). In an aqueous solution, the constructed BC/BC symmetric supercapacitor exhibits increased super capacitor behavior with a high energy density of 29.5 Whkg-1. The concept provides an efficient method for producing high-performance electrode materials for supercapacitors from conventional water treatment biomass wastes.

Keywords: supercapacitors, carbon, material science, batteries

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Authors: D. M. Bassuney, W. A. Ibrahim, Medhat A. E. Moustafa

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As awareness of the variable nature of food industrial wastewater and its environmental impact grows, a more stable treatment reactor is needed to treat such wastewater. In this paper, a performance of 5-compartment lab-scale Anaerobic Baffled Reactor (ABR) treating high strength wastewater with high pH variation was studied under three organic loading rates (OLRs). The reactor showed high COD removal efficiencies: 92.67, 97.44, and 98.19% corresponding to OLRs of 2.0, 3.0, and 4.8 KgCOD/m3 d, respectively. The first compartment showed a good buffering capacity and a distinct phase separation occurred in the ABR.

Keywords: anaerobic baffled reactor, food industrial wastewater, high strength wastewater, organic loading, pH

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Authors: Mohammad Syed Ali Molla, Mohammed Azim, Mohammad Esharuzzaman

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Centrifugal-casting machine is used in manufacturing special machine components like multi-layer journal bearing used in all internal combustion engine, steam, gas turbine and air craft turboengine where isotropic properties and high precisions are desired. Moreover, this machine can be used in manufacturing thin wall hightech machine components like cylinder liners and piston rings of IC engine and other machine parts like sleeves, and bushes. Heavy-duty machine component like railway wheel can also be prepared by centrifugal casting. A lot of technological developments are required in casting process for production of good casted machine body and machine parts. Usually defects like blowholes, surface roughness, chilled surface etc. are found in sand casted machine parts. But these can be removed by centrifugal casting machine using rotating metallic die. Moreover, die rotation, its temperature control, and good pouring practice can contribute to the quality of casting because of the fact that the soundness of a casting in large part depends upon how the metal enters into the mold or dies and solidifies. Poor pouring practice leads to variety of casting defects such as temperature loss, low quality casting, excessive turbulence, over pouring etc. Besides these, handling of molten metal is very unsecured and dangerous for the workers. In order to get rid of all these problems, the need of an automatic pouring device arises. In this research work, a robot assisted pouring device and a centrifugal casting machine are designed, developed constructed and tested experimentally which are found to work satisfactorily. The robot assisted pouring device is further modified and developed for using it in actual metal casting process. Lot of settings and tests are required to control the system and ultimately it can be used in automation of centrifugal casting machine to produce high-tech machine parts with desired precision.

Keywords: bearing, centrifugal casting, cylinder liners, robot

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Authors: S. Gariani, I. Shyha

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Cutting titanium alloys are usually accompanied with low productivity, poor surface quality, short tool life and high machining costs. This is due to the excessive generation of heat at the cutting zone and difficulties in heat dissipation due to relatively low heat conductivity of this metal. The cooling applications in machining processes are crucial as many operations cannot be performed efficiently without cooling. Improving machinability, increasing productivity, enhancing surface integrity and part accuracy are the main advantages of cutting fluids. Conventional fluids such as mineral oil-based, synthetic and semi-synthetic are the most common cutting fluids in the machining industry. Although, these cutting fluids are beneficial in the industries, they pose a great threat to human health and ecosystem. Vegetable oils (VOs) are being investigated as a potential source of environmentally favourable lubricants, due to a combination of biodegradability, good lubricous properties, low toxicity, high flash points, low volatility, high viscosity indices and thermal stability. Fatty acids of vegetable oils are known to provide thick, strong, and durable lubricant films. These strong lubricating films give the vegetable oil base stock a greater capability to absorb pressure and high load carrying capacity. This paper details preliminary experimental results when turning Ti-6Al-4V. The impact of various VO-based cutting fluids, cutting tool materials, working conditions was investigated. The full factorial experimental design was employed involving 24 tests to evaluate the influence of process variables on average surface roughness (Ra), tool wear and chip formation. In general, Ra varied between 0.5 and 1.56 µm and Vasco1000 cutting fluid presented comparable performance with other fluids in terms of surface roughness while uncoated coarse grain WC carbide tool achieved lower flank wear at all cutting speeds. On the other hand, all tools tips were subjected to uniform flank wear during whole cutting trails. Additionally, formed chip thickness ranged between 0.1 and 0.14 mm with a noticeable decrease in chip size when higher cutting speed was used.

Keywords: cutting fluids, turning, Ti-6Al-4V, vegetable oils, working conditions

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Authors: E. Kalcheva, A. Taki, Y. Hadi

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High-rises and placemaking is an understudied combination which receives more and more interest with the proliferation of this typology in many British cities. The reason for studying three major cities in England: London, Birmingham and Manchester, is to learn from the latest advances in urban design in well-developed and prominent urban environment. The analysis of several high-rise sites reveals the weaknesses in urban design of contemporary British cities and presents an opportunity to study from the implemented examples. Therefore, the purpose of this research is to analyze design approaches towards creating a sustainable and varied urban environment when high-rises are involved. The research questions raised by the study are: what is the quality of high-rises and their surroundings; what facilities and features are deployed in the research area; what is the role of the high-rise buildings in the placemaking process; what urban design principles are applicable in this context. The methodology utilizes observation of the researched area by structured questions, developed by the author to evaluate the outdoor qualities of the high-rise surroundings. In this context, the paper argues that the quality of the public realm around the high-rises is quite low, missing basic but vital elements such as plazas, public art, and seating, along with landscaping and pocket parks. There is lack of coherence, the rhythm of the streets is often disrupted, and even though the high-rises are very aesthetically appealing, they fail to create a sense of place on their own. The implications of the study are that future planning can take into consideration the critique in this article and provide more opportunities for urban design interventions around high-rise buildings in the British cities.

Keywords: high-rises, placemaking, urban design, townscape

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Authors: R. S. Rajpurohit, N. C. Santhi Srinivas, Vakil Singh

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Asymmetric stress cycling leads to accumulation of plastic strain which is called as ratcheting strain. The problem is generally associated with nuclear fuel cladding materials used in nuclear power plants and pressurized pipelines. In the present investigation, asymmetric stress controlled fatigue tests were conducted with three different parameters namely, mean stress, stress amplitude and stress rate (keeping two parameters constant and varying third parameter) to see the plastic strain accumulation and its effect on fatigue life and deformation behavior of Zircaloy-2 at 400°C. The tests were conducted with variable mean stress (45-70 MPa), stress amplitude (95-120 MPa) and stress rate (30-750 MPa/s) and tested specimens were characterized using transmission and scanning electron microscopy. The experimental results show that with the increase in mean stress and stress amplitude, the ratcheting strain accumulation increases with reduction in fatigue life. However, increase in stress rate leads to improvement in fatigue life of the material due to small ratcheting strain accumulation. Fractographs showed a decrease in area fraction of fatigue failed region.

Keywords: asymmetric cyclic loading, ratcheting fatigue, mean stress, stress amplitude, stress rate, plastic strain

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Authors: Alexia Wu, Joel Ribis, Jean-Christophe Brachet, Emmanuel Clouet, Benoit Arnal, Elodie Rouesne, Stéphane Urvoy, Justine Roubaud, Yves Serruys, Frederic Lepretre

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To enhance the safety of Light Water Reactor, accident tolerant fuel (ATF) claddings materials are under development. In the framework of CEA-AREVA-EDF collaborative program on ATF cladding materials, CEA has engaged specific studies on chromium coated zirconium alloys. Especially for Loss-of-Coolant-Accident situations, chromium coated claddings have shown some additional 'coping' time before achieving full embrittlement of the oxidized cladding, when compared to uncoated references – both tested in steam environment up to 1300°C. Nevertheless, the behavior of chromium coatings and the stability of the Zr-Cr interface under neutron irradiation remain unknown. Two main points are addressed: 1. Bulk Cr behavior under irradiation: Due to its BCC crystallographic structure, Cr is prone to Ductile-to-Brittle-Transition at quite high temperature. Irradiation could be responsible for a significant additional DBTT shift towards higher temperatures. 2. Zircaloy/Cr interface behavior under irradiation: Preliminary TEM examinations of un-irradiated samples revealed a singular Zircaloy-4/Cr interface with nanometric intermetallic phase layers. Such particular interfaces highlight questions of how they would behave under irradiation - intermetallic zirconium phases are known to be more or less stable under irradiations. Another concern is a potential enhancement of chromium diffusion into the zirconium-alpha based substrate. The purpose of this study is then to determine the behavior of such coatings after ion irradiations, as a surrogate to neutron irradiation. Ion irradiations were performed at the Jannus-Saclay facility (France). 20 MeV Kr8+ ions at 400°C with a flux of 2.8x1011 ions.cm-2.s-1 were used to irradiate chromium coatings of 1-2 µm thick on Zircaloy-4 sheets substrate. At the interface, the calculated damage is close to 10 dpa (SRIM, Quick Calculation Damage mode). Thin foil samples were prepared with FIB for both as-received and irradiated coated samples. Transmission Electron Microscopy (TEM) and in-situ tensile tests in a Scanning Electron Microscope are being used to characterize the un-irradiated and irradiated materials. High Resolution TEM highlights a great complexity of the interface before irradiation since it is formed of an alternation of intermetallic phases – C14 and C15. The interfaces formed by these intermetallic phases with chromium and zirconium show semi-coherency. Chemical analysis performed before irradiation shows some iron enrichment at the interface. The chromium coating bulk microstructures and properties are also studied before and after irradiation. On-going in-situ tensile tests focus on the capacity of chromium coatings to sustain some plastic deformation when tested up to 350°C. The stability of the Cr/Zr interface is shown after ion irradiation up to 10 dpa. This observation constitutes the first result after irradiation on these new coated claddings materials.

Keywords: accident tolerant fuel, HRTEM, interface, ion-irradiation

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Authors: Shakirat Abimbola Adesola, Shuaib Akintunde Asifat, Jelili Olalekan Amoo

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This paper presented the impact of students’ emotions on learning when receiving lectures and when taking tests. It was observed that students experience different types of emotions during the study, and this was found to have a significant effect on their academic performance. A total of one thousand six hundred and seventy-five (1675) students from the department of Computer Science in two Colleges of Education in South-West Nigeria took part in this study. The students were randomly selected for the research. Sample comprises of 968 males representing 58%, and 707 females representing 42%. A structured questionnaire, of Motivated Strategies for Learning Questionnaire (MSLQ) was distributed to the participants to obtain their opinions. Data gathered were analyzed using the IBM SPSS 20 to obtain ANOVA, descriptive analysis, stepwise regression, and reliability tests. The results revealed that emotion moderately shape students’ motivation and engagement in learning; and that self-regulation and self-determination do have significant impact on academic performance. It was further revealed that test anxiety has a significant correlation with academic performance.

Keywords: motivation, self-determination, test anxiety, academic performance, and academic engagement

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Authors: Syed Ibrahim, Syed Muneer Ahmed

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It is a global phenomenon that fitness is a pre-requisite to the desired end of optimum efficiency in elite class basketballers achieved through appropriate conditioning program. This study was undertaken to find out the effect of gymnastic oriented training program on the physical fitness and the level of technical performance of basketball players. Method: 27 basketballers were divided into 12 experimental and 15 control groups aged between 19 to 25 years. Physical fitness tests comprising of vertical jump, push-ups, chin ups, sit ups, back strength, 30 m sprint, boomerangs test, 600 m run, sit and reach, bridge up and shoulder rotation and technical skill tests like dribbling, layup shots and rebound collection were used for the study. A pre- and post-test was conducted before and after the training program of 6 weeks. Results: The results indicated no significant difference in the anthropometric measurements of age, height and weight between the experimental and control group as the ‘t’ values observed were 0.28, 1.63 and 1.60 respectively . There were significant improvements in vertical jump, push-ups, sit-ups, modified boomerang test, bridge test and shoulder rotation index with the ‘t’ values being 2.60, 3.41, 3.91, 4.02, 3.55 and 2.33 respectively. However, no significant differences existed in chin-ups, back strength, 30 m sprint and 6000 m run with the ‘t’ values being 2.08, 1.77, 1.28 and 0.80 respectively. There was significant improvement in the post-test for the technical skills tests in the experimental group with ‘t’ values being 3.65, 2.57, and 3.62 for the dribble, layup shots and rebound collection respectively. There was no significant difference in the values of the control group except in the rebound collection which showed significant difference. Conclusion: It was found that both the physical fitness and skill proficiency of the basketballers increased through the participation in the gymnastics oriented program.

Keywords: gymnastic, technical, pre-requisite, elite class

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Authors: Mohammad Javad Mehrabanpour, Mohammad Hosein Hosseini, Ali Shirazi, Dorsa Mehrabanpour

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Respiratory infections are the most important diseases that affect poultry. Ornithobacterium rhinotracheale is a bacterium that causes respiratory infections including alveolar inflation and pneumonia in birds. The aim of this study was to evaluated antibody titer against Ornitobacterium rhinotracheal in layer chicken sera after vaccination with an experimental ORT vaccine that produced in Razi Vaccine and Serum Research Institute. Cultured bacteria were inactivated by formalin, and controlled tests were conducted on it. The obtained antigens were formulated using Montanide oil and were homogenized using homogenizer. Eighty SPF chickens were kept until the age of 14 days under existing standards for temperature, humidity, and light. At the age of 14 days, chickens were divided into 3 groups. The first group included 50 chickens injected with prepared ORT vaccine, the second group, as control group, included 15 chickens injected with sterile PBS to get stress of infection and the third group included 15 chickens with no injection performed to them. All 3 groups were kept in separate cages at same room. Blood samples were regularly taken from the chickens every week for serum separation and evaluation of antibody titer. During the fifth week post vaccination, booster vaccine was injected into the chickens of vaccinated group. The chickens were inspected every day in terms of mortality as well as any injection site reactions. Three weeks after the booster injection, blood samples were taken from all chickens of all groups, and sera were isolated. The sera of immunized (vaccinated) SPF chickens with ORT vaccine as well as that of SPF chickens in the control groups were reviewed according to the recommendations of ELISA kit manufacturer to examine the chicken’s humeral immune response to the studied vaccine. Potency, stability and sterility tests were also performed on the above mentioned vaccine. Results obtained indicate high antibody titer in sera of chickens vaccinated with experimental ORT vaccine as compared with the control groups that emphasize the ability of experimentally prepared ORT vaccine to stimulate humoral immune response of chicken. After the second injection, antibody titer increased and remained almost stable up to 9 weeks after the injection. ORT vaccine can cause potency in chickens and can protect them against disease.

Keywords: antibody, layer chicken, Ornithobactrium rhinotracitis, vaccine

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Authors: Juan C. Sanchez, Jose L. Endrino, Alejandro Toro, Hugo A. Estupinan, Glenn Leighton

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For years, the reduction of friction and wear has been a matter of interest in the engineering field. Several solutions have been proposed to address this issue, including the use of lubricants and coatings to reduce the frictional forces and to increase the surface wear resistance. Alternatively, texturing processes have been used in a wide variety of materials, in many cases inspired in natural surfaces. Nature has shown how species adapt to the environment and the engineers try to understand natural surfaces for particular applications by analyzing outstanding species such as gecko for high adhesion, lotus leaves for hydrophobicity, sharks for reduced flow resistance and snakes for optimized frictional response. Texturized surfaces have shown a superior performance in terms of the frictional response in many situations, and the control of its behavior greatly depends on the manufacturing process. The focus of this work is to evaluate the tribological behavior of AISI 52100 steel samples texturized by Photochemical Machining (PCM). The surface texture was inspired by several features of the snakeskin such as aspect ratio of fibrils and mean fibril spacing. Two coatings were applied on the texturized surface, namely Diamond-like Carbon (DLC) and Molybdenum Disulphide (MoS₂), and their tribological behavior after pin-on-disk tests were compared with that of the non-texturized and uncovered surfaces. The samples were characterised through Stereoscopic Microscope (SM), Scanning Electron Microscope (SEM), Optical Microscope (OM), Profilometer, Raman Spectrometer (RS) and X-Ray Diffractometer (XRD). The Coefficient of Friction (COF) measured in pin-on-disk tests showed correlations with the sliding direction (relative to the texture features) and the aspect ratio of the texture features. Regarding the coated surfaces, the DLC and MoS₂ coating had a good performance in terms of wear rate and coefficient of friction compared with the uncoated and non-texturized surfaces. On the other hand, for the uncoated surfaces, the texture showed an influence in the tribological performance with respect to the non-texturized surface.

Keywords: coating, coefficient of friction, deterministic surface, photochemical machining

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Authors: Azwadi Mohamad, Pauzi Yahaya, Nadiah Hudi

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Earthing system for high-voltage transmission tower is designed to protect the working personnel and equipments, and to maintain the quality of supply during fault. The existing earthing system for transmission towers in TNB’s system is purposely designed for normal power frequency (low-frequency) fault conditions that take into account the step and touch voltages. This earthing design is found to be inapt for lightning (transient) condition to a certain extent, which involves a high-frequency domain. The current earthing practice of laying the electrodes radially in straight 60 m horizontal lines under the ground, in order to achieve the specified impedance value of less than 10 Ω, was deemed ineffective in reducing the high-frequency impedance. This paper introduces a new earthing design that produces low impedance value at the high-frequency domain, without compromising the performance of low-frequency impedance. The performances of this new earthing design, as well as the existing design, are simulated for various soil resistivity values at varying frequency. The proposed concentrated earthing design is found to possess low TFR value at both low and high-frequency. A good earthing design should have a fine balance between compact and radial electrodes under the ground.

Keywords: earthing design, high-frequency, lightning, tower footing impedance

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Authors: Chiu-Pin Wei

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This research aims to explore the impact of music preferences on the emotional well-being of military academy students, recognizing the potential long-term implications for their high-stress careers post-graduation. Given the significance of positive emotion regulation in military personnel, this study focuses on understanding the types of music preferred by military cadets and analyzing how these preferences correlate with their emotional states. The study employs a quantitative approach, utilizing the Music Category Scale and Mood Scale to collect data. Statistical tools, such as Statistical Product and Service Solutions (SPSS), are employed for inferential analysis, including t-tests for emotional responses to instrumental and vocal music, one-way variance analysis for different demographic factors (grades, genders, and music listening frequencies), and Pearson's correlation to examine the relationship between music preferences and moods of military students.

Keywords: music preference, emotional regulation, military academic students, SPASS

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Authors: Manikandakumar Shunmugavel, Ashwin Polishetty, Moshe Goldberg, Junior Nomani, Guy Littlefair

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Selective laser melting (SLM), a promising additive manufacturing (AM) technology, has a huge potential in the fabrication of Ti-6Al-4V near-net shape components. However, poor surface finish of the components fabricated from this technology requires secondary machining to achieve the desired accuracy and tolerance. Therefore, a systematic understanding of the machinability of SLM fabricated Ti-6Al-4V components is paramount to improve the productivity and product quality. Considering the significance of machining in SLM fabricated Ti-6Al-4V components, this research aim is to study the influence of build orientation on machinability characteristics by performing low speed orthogonal cutting tests. In addition, the machinability of SLM fabricated Ti-6Al-4V is compared with conventionally produced wrought Ti-6Al-4V to understand the influence of SLM technology on machining. This paper is an attempt to provide evidence to the hypothesis associated that build orientation influences cutting forces, chip formation and surface integrity during orthogonal cutting of SLM Ti-6Al-4V samples. Results obtained from the low speed orthogonal cutting tests highlight the practical importance of microstructure and build orientation on machinability of SLM Ti-6Al-4V.

Keywords: additive manufacturing, build orientation, machinability, titanium alloys (Ti-6Al-4V)

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Authors: Carol Leroy

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This presentation focuses on the analysis qualitative case studies in the graduate education of reading specialists. The presentation describes the development and application of an integrated conceptual framework for reading specialist education, drawing on Robert Stake’s work on case study research, Kenneth Zeichner’s work on professional learning, and various tools for reading assessment (e.g. the Qualitative Reading Inventory). Social constructivist theory is used to provide intersecting links between the various influences on the processes used to assess and teaching reading within the case study framework. Illustrative examples are described to show the application of the framework in reading specialist education in a teaching clinic at a large urban university. Central to education of reading specialists in this teaching clinic is the collection, analysis and interpretation of data for the design and implementation of reading and writing programs for struggling readers and writers. The case study process involves the integrated interpretation of data, which is central to qualitative case study inquiry. An emerging theme in this approach to graduate education is the ambiguity and uncertainty that governs work with the adults and children who attend the clinic for assistance. Tensions and contradictions are explored insofar as they reveal overlapping but intersecting frameworks for case study analysis in the area of literacy education. An additional theme is the interplay of multiple layers of data with a resulting depth that goes beyond the practical need of the client and toward the deeper pedagogical growth of the reading specialist. The presentation makes a case for the value of qualitative case studies in reading specialist education. Further, the use of social constructivism as a unifying paradigm provides a robustness to the conceptual framework as a tool for understanding the pedagogy that is involved.

Keywords: assessment, case study, professional education, reading

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Authors: Abdelmaoula Mahamoud Tahir, Sedat Sert

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The possibility of improving the shear strength of unsaturated clayey soil with the addition of olivine was investigated in this paper. Unconsolidated undrained triaxial tests (UU), under different cell pressures (namely: 100 kPa and 200 kPa), with varying percentages of olivine (10% and 20% by weight) and with one day, 28 days, and 56 days curing times, were performed to determine the shear strength of the soil. The increase in strength was observed as a function of the increase in olivine content. An olivine content of 25% was determined as the optimum value to achieve the targeted improvement for both cure times. A comparative study was also conducted between clay samples treated with only olivine and others in the presence of potassium hydroxide (KOH). Clay samples treated with olivine and activated with potassium hydroxide (KOH) had higher shear strength than non-activated olivine-treated samples. It was determined that the strength of the clay samples treated with only olivine did not increase over time and added resistance only with the high specific gravity of olivine. On the other hand, the samples activated with potassium hydroxide (KOH) added to the resistance with high specific gravity and the chemical bonds of olivine. Morphological and mineralogical analyzes were carried out in this study to see and analyze the chemical bonds formed after the reaction. The main components of this improvement were the formation of magnesium-aluminate-hydrate and magnesium-silicate-hydrate. Compared to older methods such as cement addition, these results show that in stabilizing clayey soils, olivine additive offers an energy-efficient alternative for reducing carbon dioxide emissions.

Keywords: ground stabilization, clay, olivine additive, KOH, microstructure

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Authors: Xinyi Xu

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This study conducts a detailed examination of Asian stock markets over the period from 2008 to 2023, with a focus on the dynamics of cointegration and their relevance for long-term investment strategies. Specifically, we assess the co-movement and potential for pairs trading—a strategy where investors take opposing positions on two stocks, indices, or financial instruments that historically move together. For example, we explore the relationship between the Nikkei 225 (N225), Japan’s benchmark stock index, and the Straits Times Index (STI) of Singapore, as well as the relationship between the Korea Composite Stock Price Index (KS11) and the STI. The methodology includes tests for normality, stationarity, cointegration, and the application of Vector Error Correction Modeling (VECM). Our findings reveal significant long-term relationships between these pairs, indicating opportunities for pairs trading strategies. Furthermore, the research underscores the challenges posed by model instability and the influence of major global incidents, which are identified as structural breaks. These findings pave the way for further exploration into the intricacies of financial market dynamics.

Keywords: normality tests, stationarity, cointegration, VECM, pairs trading

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Authors: Mehwish Sarfaraz Ahmad

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Background: There is a prevailing perception in Pakistan that private hospitals offer better services than government hospitals. Unfortunately, Pakistan faces challenges in providing efficient healthcare due to limited resources and management capabilities, resulting in demotivation among healthcare workers. Aim: The purpose of this study was to conduct a comprehensive assessment of the occupational health and well-being of healthcare workers in both public and private sector tertiary care hospitals in Lahore, Pakistan, to compare the well-being of healthcare professionals in these two sectors and investigate the influence of workplace culture and experiences on their overall health. Methods: A cross-sectional study was conducted using a validated International Questionnaire, and data from 440 participants was collected using a stratified random sampling technique from a diverse group of healthcare professionals from the public and private tertiary care hospitals in Lahore, Pakistan. The researcher conducted a comparative analysis using appropriate statistical tests, such as Anova, t-tests, chi-square tests, and regression analysis, to explore potential relationships between various factors. Results: The majority of respondents (70.2%) reported their health as "Good" or "Very good, a small percentage (8.2%) rated their health as "Poor," while 24.1% considered their health as "Fair". 39.6% reported being satisfied with their workplace culture, while a majority of 60.4% indicated being unsatisfied with their workplace culture. Results showed that workplace culture has a positive correlation with the overall health and well-being of healthcare professionals. The study found significant differences in health ratings, prevalence of chronic health conditions, workplace culture, and safety perceptions between healthcare professionals in public and private sector tertiary care hospitals. Conclusion: The study's findings emphasize the significance of promoting a positive workplace culture, ensuring workplace safety, and addressing chronic health conditions among healthcare workers.

Keywords: occupational health and well-being, workplace culture, frequency of fatigue, availabity of benefits

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Authors: Lalita Khuna, Sugalya Amatachaya, Pipatana Amatachaya, Thiwabhorn Thaweewannakij, Pattra Wattanapan

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The five times sit-to-stand test (FTSST) has been widely used to quantify lower extremity motor strength (LEMS), dynamic balance ability, and risk of falls in many individuals. Recently, it has been used in ambulatory patients with spinal cord injury (SCI) but variously using with or without hands according to patients’ ability. This difference might affect the validity of the test in these individuals. Thus, this study assessed the concurrent validity of the FTSST in ambulatory individuals with SCI, separately for those who could complete the test with or without hands using LEMS and standard functional measures as gold standards. Moreover, the data of the tests from those who completed the FTSST with and without hands were compared. A total of 56 ambulatory participants with SCI who could complete sit-to-stand with or without hands were assessed for the time to complete the FTSST according to their ability. Then they were assessed for their LEMS scores and functional abilities, including the 10-meter walk test (10MWT), the walking index for spinal cord injury II (WISCI II), the timed up and go test (TUGT), and the 6-minute walk test (6MWT). The Mann-Whitney U test was used to compare the different findings between the participants who performed the FTSST with and without hands. The Spearman rank correlation coefficient (ρ) was applied to analyze the levels of correlation between the FTSST and standard tests (LEMS scores and functional measures). There were significant differences in the data between the participants who performed the test with and without hands (p < 0.01). The time to complete the FTSST of the participants who performed the test without hands showed moderate to strong correlation with total LEMS scores and all functional measures (ρ = -0.71 to 0.69, p < 0.001). On the contrary, the FTSST data of those who performed the test with hands were significantly correlated only with the 10MWT, TUGT, and 6MWT (ρ = -0.47 to 0.57, p < 0.01). The present findings confirm the concurrent validity of the FTSST when performed without hands for LEMS and functional mobility necessary for the ability of independence and safety of ambulatory individuals with SCI. However, the test using hands distort the ability of the outcomes to reflect LEMS and WISCI II that reflect lower limb functions. By contrast, the 10MWT, TUGT, and 6MWT allowed upper limb contribution in the tests. Therefore, outcomes of these tests showed a significant correlation to the outcomes of FTSST when assessed using hands. Consequently, the use of FTSST with or without hands needs to consider the clinical application of the outcomes, i.e., to reflect lower limb functions or mobility of the patients.

Keywords: mobility, lower limb muscle strength, clinical test, rehabilitation

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Authors: Jamie A. Prowse Turner, Jamie I. D. Campbell, Valerie A. Thompson

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The objective of the current research was to use a dual-process theory framework to explain these age-related differences in reasoning. Seventy-two older (M = 80.0 years) and 72 younger (M = 24.6 years) adults were given a variety of reasoning tests (i.e., a syllogistic task, base rate task, the Cognitive Reflection Test, and a perspective manipulation), as well as independent tests of capacity (working memory, processing speed, and inhibition), thinking styles, and metacognitive ability, to account for these age-related differences. It was revealed that age-related differences were limited to problems that required Type 2 processing and were related to differences in cognitive capacity, individual difference factors, and strategy choice. Furthermore, older adults’ performance can be improved by reasoning from another’s’ perspective and cannot, at this time, be explained by metacognitive differences between young and older adults. All of these findings fit well within a dual-process theory of reasoning, which provides an integrative framework accounting for previous findings and the findings presented in the current manuscript.

Keywords: aging, dual-process theory, performance, reasoning ability

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Authors: Guang Zou, Kian Banisoleiman, Arturo González

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Crack initiation and propagation threatens structural integrity of welded joints and normally inspections are assigned based on crack propagation models. However, the approach based on crack propagation models may not be applicable for some high-quality welded joints, because the initial flaws in them may be so small that it may take long time for the flaws to develop into a detectable size. This raises a concern regarding the inspection planning of high-quality welded joins, as there is no generally acceptable approach for modeling the whole fatigue process that includes the crack initiation period. In order to address the issue, this paper reviews treatment methods for crack initiation period and initial crack size in crack propagation models applied to inspection planning. Generally, there are four approaches, by: 1) Neglecting the crack initiation period and fitting a probabilistic distribution for initial crack size based on statistical data; 2) Extrapolating the crack propagation stage to a very small fictitious initial crack size, so that the whole fatigue process can be modeled by crack propagation models; 3) Assuming a fixed detectable initial crack size and fitting a probabilistic distribution for crack initiation time based on specimen tests; and, 4) Modeling the crack initiation and propagation stage separately using small crack growth theories and Paris law or similar models. The conclusion is that in view of trade-off between accuracy and computation efforts, calibration of a small fictitious initial crack size to S-N curves is the most efficient approach.

Keywords: crack initiation, fatigue reliability, inspection planning, welded joints

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Authors: Payam Rasoulnia, Seyyed Mohammad Mousavi

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Heavy fuel oil firing power plants produce huge amounts of ashes as solid wastes, which seriously need to be managed and processed. Recycling precious metals of V and Ni from these oil-fired ashes which are considered as secondary sources of metals recovery, not only has a great economic importance for use in industry, but also it is noteworthy from the environmental point of view. Vanadium is an important metal that is mainly used in the steel industry because of its physical properties of hardness, tensile strength, and fatigue resistance. It is also utilized in oxidation catalysts, titanium–aluminum alloys and vanadium redox batteries. In the present study bioleaching of vanadium and nickel from an oil-fired ash sample was conducted using Aspergillus niger fungus. The experiments were carried out using spent-medium bioleaching method in both Erlenmeyer flasks and also bubble column bioreactor, in order to compare them together. In spent-medium bioleaching the solid waste is not in direct contact with the fungus and consequently the fungal growth is not retarded and maximum organic acids are produced. In this method the metals are leached through biogenic produced organic acids present in the medium. In shake flask experiments the fungus was cultured for 15 days, where the maximum production of organic acids was observed, while in bubble column bioreactor experiments a 7 days fermentation period was applied. The amount of produced organic acids were measured using high performance liquid chromatography (HPLC) and the results showed that depending on the fermentation period and the scale of experiments, the fungus has different major lixiviants. In flask tests, citric acid was the main produced organic acid by the fungus and the other organic acids including gluconic, oxalic, and malic were excreted in much lower concentrations, while in the bioreactor oxalic acid was the main lixiviant and it was produced considerably. In Erlenmeyer flasks during 15 days fermentation of Aspergillus niger, 8080 ppm citric acid and 1170 ppm oxalic acid was produced, while in bubble column bioreactor over 7 days of fungal growth, 17185 ppm oxalic acid and 1040 ppm citric acid was secreted. The leaching tests using the spent-media obtained from both of fermentation experiments, were performed at the same conditions of leaching duration of 7 days, leaching temperature of 60 °C and pulp density up to 3% (w/v). The results revealed that in Erlenmeyer flask experiments 97% of V and 50% of Ni were extracted while using spent medium produced in bubble column bioreactor, V and Ni recoveries were achieved to 100% and 33%, respectively. These recovery yields indicate that in both scales almost total vanadium can be recovered, while nickel recovery was lower. With help of the bioreactor spent-medium nickel recovery yield was lower than that of obtained from the flask experiments, which it could be due to precipitation of some values of Ni in presence of high levels of oxalic acid existing in its spent medium.

Keywords: Aspergillus niger, bubble column bioreactor, oil-fired ash, spent-medium bioleaching

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Authors: Vera Wilden, Benno Hoffmeister, Georgios Balaskas, Lukas Rauber, Burkhard Walter

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Light-weight timber frame elements represent an efficient structural solution for wooden multistory buildings. The wall elements of such buildings – which act as shear diaphragms- provide lateral stiffness and resistance to wind and seismic loads. The tendency towards multi-story structures leads to challenges regarding the prediction of stiffness, strength and ductility of the buildings. Lightweight timber frame elements are built up of several structural parts (sheeting, fasteners, frame, support and anchorages); each of them contributing to the dynamic response of the structure. This contribution describes the experimental and numerical investigation and development of enhanced lightweight timber frame buildings. These developments comprise high-performance timber frame walls with the variable arrangements of sheathing planes and dissipative anchors at the base of the timber buildings, which reduce damages to the timber structure and can be exchanged after significant earthquakes. In order to prove the performance of the developed elements in the context of a real building a full-scale two-story building core was designed and erected in the laboratory and tested experimentally for its seismic performance. The results of the tests and a comparison of the test results to the predicted behavior are presented. Observation during the test also reveals some aspects of the design and details which need to consider in the application of the timber walls in the context of the complete building.

Keywords: dissipative anchoring, full scale test, push-over-test, wood shear walls

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Authors: Kyoung-il Do, Byung-seok Lee, Hee-guk Chae, Jeong-yun Seo Yong-seo Koo

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In this paper, a Silicon Controlled Rectifier (SCR)-based Electrostatic Discharge (ESD) protection circuit with high holding voltage and high robustness characteristics is proposed. Unlike conventional SCR, the proposed circuit has low trigger voltage and high holding voltage and provides effective ESD protection with latch-up immunity. In addition, the TCAD simulation results show that the proposed circuit has better electrical characteristics than the conventional SCR. A stack technology was used for voltage-specific applications. Consequentially, the proposed circuit has a trigger voltage of 17.60 V and a holding voltage of 3.64 V.

Keywords: ESD, SCR, latch-up, power clamp, holding voltage

Procedia PDF Downloads 392

Authors: Tyler Palma, Praveen Damasus, Michael Munther, Mehrdad Mohsenizadeh, Keivan Davami

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The advancement of additive manufacturing, in both research and commercial realms, is highly dependent upon continuing innovations and creativity in materials and designs. Additive manufacturing shows great promise towards revolutionizing various industries, due largely to the fact that design data can be used to create complex products and components, on demand and from the raw materials, for the end user at the point of use. However, it will be critical that the material properties of additively-made parts for engineering purposes be fully understood. As it is a relatively new additive manufacturing method, the response of properties of Multi Jet Fusion (MJF) produced parts to different printing parameters has not been well studied. In this work, testing of mechanical and tribological properties MJF-printed Polyamide 12 parts was performed to determine whether printing orientation in this method results in significantly different part performances. Material properties were studied at macro- and nanoscales. Tensile tests, in combination with tribology tests including steady-state wear, were performed. Results showed a significant difference in resultant part characteristics based on whether they were printed in a vertical or horizontal orientation. Tensile performance of vertically and horizontally printed samples varied, both in ultimate strength and strain. Tribology tests showed that printing orientation has notable effects on the resulting mechanical and wear properties of tested surfaces, due largely to layer orientation and the presence of unfused fused powder grain inclusions. This research advances the understanding of how print orientation affects the mechanical properties of additively manufactured structures, and also how print orientation can be exploited in future engineering design.

Keywords: additive manufacturing, indentation, nano mechanical characterization, print orientation

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Authors: Elie Awwad, Bilal Hamad, Mounir Mabsout, Helmi Khatib

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The paper reports test results on the long-term behavior of sustainable hemp-concrete material prepared in research work conducted at the American University of Beirut. The tests results are in terms of compressive and splitting tensile tests conducted on standard 150x300 mm cylinders. A control mix without fibers, one polypropylene-concrete mix, and ten hemp-concrete mixes were prepared with different percentages of industrial hemp fibers and reduced coarse aggregate contents. The objective was to investigate the strength properties of hemp-reinforced concrete at 1.5 years age as compared with control mixes. The results indicated that both the compressive strength and the splitting tensile strength results of all tested cylinders increased as compared with the 28-days values. Also, the difference between the hemp-concrete samples and the control samples at 28 days was maintained at 1.5 years age indicating that hemp fibers did not exhibit any negative effect on the long-term strength properties of concrete.

Keywords: hemp-reinforced concrete, natural fibers, compressive strength, splitting tensile strength

Procedia PDF Downloads 360