Search results for: wind tunnel test

Authors: Y. Khulief, S. Bashmal, S. Said, D. Al-Otaibi, K. Mansour

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The prediction of flow rates at which the vibration-induced instability takes place in tubular heat exchangers due to cross-flow is of major importance to the performance and service life of such equipment. In this paper, the semi-analytical model for square tube arrays was extended and utilized to study the triangular tube patterns. A laboratory test rig with instrumented test section is used to measure the fluidelastic coefficients to be used for tuning the mathematical model. The test section can be made of any bundle pattern. In this study, two test sections were constructed for both the normal triangular and the rotated triangular tube arrays. The developed scheme is utilized in predicting the onset of flow-induced instability in the two triangular tube arrays. The results are compared to those obtained for two other bundle configurations. The results of the four different tube patterns are viewed in the light of TEMA predictions. The comparison demonstrated that TEMA guidelines are more conservative in all configurations considered

Keywords: fluid-structure interaction, cross-flow, heat exchangers,

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Authors: Ashika Govender

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This study seeks to determine whether Okun’s Law is valid for the South African economy, using time series data for the period 2004 to 2014. The data were accessed from the South African Reserve Bank and Stats SA. The stationarity of the variables was analysed by applying unit root tests via the Augmented Dickey-Fuller test (ADF), the Phillips-Perron (PP) test, and the Kwiatkowski–Phillips–Schmidt–Shin test (KPSS) test. The study used an ordinary least square (OLS) model in analysing the dynamic version of Okun’s law. The Error Correction Model (ECM) was used to analyse the short-run impact of GDP growth on unemployment, as well as the speed of adjustment. The results indicate a short run and long run relationship between unemployment rate and GDP growth rate in period 2004q1-2014q4, suggesting that Okun’s law is valid for the South African economy. With a 1 percent increase in GDP, unemployment can decrease by 0.13 percent, ceteris paribus. The research culminates in important policy recommendations, highlighting the relationship between unemployment and economic growth in the spirit of the National Development Plan.

Keywords: unemployment, economic growth, Okun's law, South Africa

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Authors: Jiri Cecrdle

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This paper describes the concept of the W-WING whirl flutter aeroelastic demonstrator. Whirl flutter is the specific case of flutter that accounts for the additional dynamic and aerodynamic influences of the engine rotating parts. The instability is driven by motion-induced unsteady aerodynamic propeller forces and moments acting in the propeller plane. Whirl flutter instability is a serious problem that may cause the unstable vibration of a propeller mounting, leading to the failure of an engine installation or an entire wing. The complicated physical principle of whirl flutter required the experimental validation of the analytically gained results. W-WING aeroelastic demonstrator has been designed and developed at Czech Aerospace Research Centre (VZLU) Prague, Czechia. The demonstrator represents the wing and engine of the twin turboprop commuter aircraft. Contrary to the most of past demonstrators, it includes a powered motor and thrusting propeller. It allows the changes of the main structural parameters influencing the whirl flutter stability characteristics. Propeller blades are adjustable at standstill. The demonstrator is instrumented by strain gauges, accelerometers, revolution-counting impulse sensor, sensor of airflow velocity, and the thrust measurement unit. Measurement is supported by the in house program providing the data storage and real-time depiction in the time domain as well as pre-processing into the form of the power spectral densities. The engine is linked with a servo-drive unit, which enables maintaining of the propeller revolutions (constant or controlled rate ramp) and monitoring of immediate revolutions and power. Furthermore, the program manages the aerodynamic excitation of the demonstrator by the aileron flapping (constant, sweep, impulse). Finally, it provides the safety guard to prevent any structural failure of the demonstrator hardware. In addition, LMS TestLab system is used for the measurement of the structure response and for the data assessment by means of the FFT- and OMA-based methods. The demonstrator is intended for the experimental investigations in the VZLU 3m-diameter low-speed wind tunnel. The measurement variant of the model is defined by the structural parameters: pitch and yaw attachment stiffness, pitch and yaw hinge stations, balance weight station, propeller type (duralumin or steel blades), and finally, angle of attack of the propeller blade 75% section (). The excitation is provided either by the airflow turbulence or by means of the aerodynamic excitation by the aileron flapping using a frequency harmonic sweep. The experimental results are planned to be utilized for validation of analytical methods and software tools in the frame of development of the new complex multi-blade twin-rotor propulsion system for the new generation regional aircraft. Experimental campaigns will include measurements of aerodynamic derivatives and measurements of stability boundaries for various configurations of the demonstrator.

Keywords: aeroelasticity, flutter, whirl flutter, W WING demonstrator

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Authors: Rinku Varghese, S. Chandrakaran, K. Rangaswamy

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The standard one-dimensional consolidation test is used to find the consolidation behaviour of artificially consolidated organic soils. Incremental loading tests were conducted on the clay without and with organic matter. The study was conducted with soil having different organic content keeping all other parameters constant. The tests were conducted on clay and artificially prepared organic soil sample at different vertical pressure. The load increment ratio considered for the test is equal to one. Artificial organic soils are used for the test by adding starch to the clay. The percentage of organic content in starch is determined by adding 5% by weight starch into the clay (inorganic soil) sample and corresponding change in organic content of soil was determined. This was expressed as percentage by weight of starch, and it was found that about 95% organic content in the soil sample. Accordingly percentage of organic content fixed and added to the sample for testing to understand the consolidation behaviour clayey soils with organic content. A detailed study of the results obtained from IL test was investigated. The main items investigated were (i) coefficient of consolidation (cv), (ii) coefficient of volume compression (mv), (iii) coefficient of permeability (k). The consolidation parameter obtained from IL test was used for determining the creep strain and creep parameter and also predicting their variation with vertical stress and organic content.

Keywords: consolidation, secondary compression, creep, starch

Procedia PDF Downloads 281

Authors: Atoum Abdullah

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The purpose of this research is to determine the extent to which computer animation and narration affect students’ understanding of complex scientific concepts and improve their exam performance, this is compared to traditional lectures that include PowerPoints with texts and static images. A mixed-method design in data collection was used, including quantitative and qualitative data. Quantitative data was collected using a pre and post-test method and a close-ended questionnaire. Qualitative data was collected through an open-ended questionnaire. A pre and posttest strategy was used to measure the level of students’ understanding with and without the use of animation. The test included multiple-choice questions to test factual knowledge, open-ended questions to test conceptual knowledge, and to label the diagram questions to test application knowledge. The results showed that students on average, performed significantly higher on the posttest as compared to the pretest on all areas of acquired knowledge. However, the increase in the posttest score with respect to the acquisition of conceptual and application knowledge was higher compared to the increase in the posttest score with respect to the acquisition of factual knowledge. This result demonstrates that animation is more beneficial when acquiring deeper, conceptual, and cognitive knowledge than when only factual knowledge is acquired.

Keywords: animation, narration, science, teaching

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Authors: Sergio Luiz da Costa Junior, Carolina Fofonka Palomino, Paulo Cesar Lodi

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The use of light landfills is an effective solution for road works in soft ground sites, such as Rio de Janeiro (RJ) and Santos (SP) - the Southeastern Brazilian coast. The technique consists in replacing the topsoil by expandable polystyrene (EPS) geofoam, lined with geomembrane to prevent the attack of chemical products.Thus, knowing the interface shear strength of those materials is important in projects to avoid rupturing the system. The purpose of this paper is to compare the shear strength in the geomembrane-EPS interfaces by the direct shear test. The tests were performed under the dry and saturated condition, and four kind of high-density polyethylene (HDPE) 2,00mm geomembranes were used, smooth and texturized - manufactured in the flat die and blown film process. It was found that the shear strength is directly influenced by the roughness of the geomembrane, showed higher friction angle in the textured geomembrane. The direct shear test, in the saturated condition, also showed smaller friction angle than the now-wetted test.

Keywords: geofoam, geomembrane, soft ground, strength shear

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Authors: Martha Serrano-Arias, Martha Frías-Armenta

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Significant results have been found both supporting universality of emotion recognition and cultural background influence. Thus, the aim of this research was to test a Mexican version of the MTSI in different cultures to find differences in their performance. The MTSI-Mx assesses through a scenario approach were subjects must evaluate real persons. Two target persons were used for the construction, a man (FS) and a woman (AD). The items were grouped in four variables: Picture, Video, and FS and AD scenarios. The test was applied to 201 students from Mexico and Germany. T-test for picture and FS scenario show no significance. Video and AD had a significance at the 5% level. Results show slight differences between cultures, although a more comprehensive research is needed to conclude which culture can perform better in this kind of assessments.

Keywords: emotion recognition, MTSI, social intelligence, transcultural study

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Authors: Khaled M. Khader, Mamdouh I. Elimy, Omayma A. Nada

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Sustainable development is the nominal goal of most countries at present. In general, fossil fuels are the development mainstay of most world countries. Regrettably, the fossil fuel consumption rate is very high, and the world is facing the problem of conventional fuels depletion soon. In addition, there are many problems of environmental pollution resulting from the emission of harmful gases and vapors during fuel burning. Thus, clean, renewable energy became the main concern of most countries for filling the gap between available energy resources and their growing needs. There are many renewable energy sources such as wind, solar and wave energy. Energy can be obtained from the motion of sea waves almost all the time. However, power generation from solar or wind energy is highly restricted to sunny periods or the availability of suitable wind speeds. Moreover, energy produced from sea wave motion is one of the cheapest types of clean energy. In addition, renewable energy usage of sea waves guarantees safe environmental conditions. Cheap electricity can be generated from wave energy using different systems such as oscillating bodies' system, pendulum gate system, ocean wave dragon system and oscillating water column device. In this paper, a multi-criteria model has been developed using Analytic Hierarchy Process (AHP) to support the decision of selecting the most effective system for generating power from sea waves. This paper provides a widespread overview of the different design alternatives for sea wave energy converter systems. The considered design alternatives have been evaluated using the developed AHP model. The multi-criteria assessment reveals that the off-shore Oscillating Water Column (OWC) system is the most appropriate system for generating power from sea waves. The OWC system consists of a suitable hollow chamber at the shore which is completely closed except at its base which has an open area for gathering moving sea waves. Sea wave's motion pushes the air up and down passing through a suitable well turbine for generating power. Improving the power generation capability of the OWC system is one of the main objectives of this research. After investigating the effect of some design modifications, it has been concluded that selecting the appropriate settings of some effective design parameters such as the number of layers of Wells turbine fans and the intermediate distance between the fans can result in significant improvements. Moreover, simple dynamic analysis of the Wells turbine is introduced. Furthermore, this paper strives for comparing the theoretical and experimental results of the built experimental prototype.

Keywords: renewable energy, oscillating water column, multi-criteria selection, Wells turbine

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Authors: Sh. Heidari, A. J. Andrews, A. Oberoi

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Electrochemical storage of hydrogen in activated carbon electrodes as part of a reversible fuel cell offers a potentially attractive option for storing surplus electrical energy from inherently variable solar and wind energy resources. Such a system – which we have called a proton flow battery – promises to have a roundtrip energy efficiency comparable to lithium ion batteries, while having higher gravimetric and volumetric energy densities. In this paper, a theoretical model is presented of the process of H+ ion (proton) conduction through an acid electrolyte into a highly porous activated carbon electrode where it is neutralised and absorbed on the inner surfaces of pores. A Butler-Volmer type equation relates the rate of adsorption to the potential difference between the activated carbon surface and the electrolyte. This model for the hydrogen storage electrode is then incorporated into a more general computer model based on MATLAB software of the entire electrochemical cell including the oxygen electrode. Hence a theoretical voltage-current curve is generated for given input parameters for a particular activated carbon electrode. It is shown that theoretical VI curves produced by the model can be fitted accurately to experimental data from an actual electrochemical cell with the same characteristics. By obtaining the best-fit values of input parameters, such as the exchange current density and charge transfer coefficient for the hydrogen adsorption reaction, an improved understanding of the adsorption reaction is obtained. This new model will assist in designing improved proton flow batteries for storing solar and wind energy.

Keywords: electrochemical hydrogen storage, proton flow battery, butler-volmer equation, activated carbon

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Authors: S. Chowdhury, A. Corlett

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Large tsunamis strike the British Columbia coast every few hundred years. The Cascadia Subduction Zone, which extends along the Pacific coast from Vancouver Island to Northern California is one of the most seismically active regions in Canada. Significant earthquakes have occurred in this region, including the 1700 Cascade Earthquake with an estimated magnitude of 9.2. Based on geological records, experts have predicted a 'great earthquake' of a similar magnitude within this region may happen any time. This earthquake is expected to generate a large tsunami that could impact the coastal communities on Vancouver Island. Since many of these communities are in remote locations, they are more likely to be vulnerable, as the post-earthquake relief efforts would be impacted by the damage to critical road infrastructures. To assess the coastal vulnerability within these communities, a hydrodynamic model has been developed using MIKE-21 software. We have considered a 500 year probabilistic earthquake design criteria including the subsidence in this model. The bathymetry information was collected from Canadian Hydrographic Services (CHS), and National Oceanic Atmospheric and Administration (NOAA). The arial survey was conducted using a Cessna-172 aircraft for the communities, and then the information was converted to generate a topographic digital elevation map. Both survey information was incorporated into the model, and the domain size of the model was about 1000km x 1300km. This model was calibrated with the tsunami occurred off the west coast of Moresby Island on October 28, 2012. The water levels from the model were compared with two tide gauge stations close to the Vancouver Island and the output from the model indicates the satisfactory result. For this study, the design water level was considered as High Water Level plus the Sea Level Rise for 2100 year. The hourly wind speeds from eight directions were collected from different wind stations and used a 200-year return period wind speed in the model for storm events. The regional model was set for 12 hrs simulation period, which takes more than 16 hrs to complete one simulation using double Xeon-E7 CPU computer plus a K-80 GPU. The boundary information for the local model was generated from the regional model. The local model was developed using a high resolution mesh to estimate the coastal flooding for the communities. It was observed from this study that many communities will be effected by the Cascadia tsunami and the inundation maps were developed for the communities. The infrastructures inside the coastal inundation area were identified. Coastal vulnerability planning and resilient design solutions will be implemented to significantly reduce the risk.

Keywords: tsunami, coastal flooding, coastal vulnerable, earthquake, Vancouver, wave propagation

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Authors: Abdullahi Garba

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The study investigated the effects of practical activities on performance among biology students in Zaria education zone, Kaduna State, Nigeria. The population consists of 18 public schools in the Zaria Education Zone with a total number of 4,763 students. A random sample of 115 students was selected from the population in the study area. The study design was quasi-experimental, which adopted the pre-test, post-test experimental, and control group design. The experimental group was exposed to practical activities, while the control group was taught with the lecture method. A validated instrument, a biology performance test (BPT) with a reliability coefficient of 0.82, was used to gather data which were analyzed using a t-test and paired sample t-test. Two research questions and hypotheses guided the study. The hypotheses were tested at p≤0.05 level of significance. Findings revealed that: there was a significant difference in the academic performance of students exposed to practical activities compared to their counterparts; there was no significant difference in performance between male and female Biology students exposed to practical activities. The recommendation given was that practical activities should be encouraged in the teaching and learning of Biology for better understanding. The Federal and State Ministry of Education should sponsor biology teachers for training and retraining of teachers to improve the academic performance of students in the subject.

Keywords: biology, practical, activity, performance

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Authors: Myisha Ahmad, G. M. Jahid Hasan

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Electricity is the pinnacle of human civilization. At present, the growing concerns over significant climate change have intensified the importance of the use of renewable energy technologies for electricity generation. The interest is primarily due to better energy security, smaller environmental impact and providing a sustainable alternative compared to the conventional energy sources. Solar power, wind, biomass, tidal power, and wave power are some of the most reliable sources of renewable energy. Ocean approximately holds 2×10³ TW of energy and has the largest renewable energy resource on the planet. Ocean energy has many forms namely, encompassing tides, ocean circulation, surface waves, salinity and thermal gradients. Ocean tide in particular, associates both potential and kinetic energy. The study is focused on the latter concept that deals with tidal current energy conversion technologies. Tidal streams or marine currents generate kinetic energy that can be extracted by marine current energy devices and converted into transmittable energy form. The principle of technology development is very comparable to that of wind turbines. Conversion of marine tidal resources into substantial electrical power offers immense opportunities to countries endowed with such resources and this work is aimed at addressing such prospects of Bangladesh. The study analyzed the extracted current velocities from numerical model works at several locations in the Bay of Bengal. Based on current magnitudes, directions and available technologies the most fitted locations were adopted and possible annual generation capacity was estimated. The paper also examines the future prospects of tidal current energy along the Bay of Bengal and establishes a constructive approach that could be adopted in future project developments.

Keywords: bay of Bengal, energy potential, renewable energy, tidal current

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Authors: A. Hira Masood, B. Umer Hameed, C. Ezza Nasir

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Contemporary studies support the strong co-relation between psychology and design. This study elaborates how different psychological personality test can help a fashion designer to judge the needs of their clients with respect to have products which will satisfy the client's request concerning costumised clothing. This study will also help the designer to improve the lacking in the personality and will enable him to put his effort in required areas for grooming the customer, control and direct organization regarding quality maintenance. The use of psychology test to support the choice of certain design strategies that how the right clothing can make client a better intellectual with enhanced self-esteem and confidence. Different projective personality test are being used to suggest to evaluate personality traits. The Rorschach Inkblot Test is projective mental comprising of 10 ink-blots synonymous with the clinical brain research. Lüsher Color Diagnostics measures a person’s psycho physical state, his or her ability to withstand stress to perform and communicate. HTP is a projective responsibility test measuring self-perception, attitudes. The TAT test intend to evaluate a person’s patterns of thoughts, attitudes, observation, capacity and emotional response to this ambiguous test materials. No doubt designers are already crucially redesigning the individuals by their attires, but to expose the behavioral mechanism of the customer, designers should be able to recognize the hidden complexity behind his client by using the above mentioned methods. The study positively finds the design and psychology need to become substantially contacted in order to create a new regime of norms to groom a personality under the concentration and services of a fashion designer in terms of clothing, This interactive activity altimately upgrade design team to help customers to find the suited way to satisfy their needs and wishes, offer client relible relationship and quality management services, and to become more disereable.

Keywords: projective personality tests, customized clothing, Rorschach Inkblot test, TAT, HTP, Lüsher color diagnostics, quality management services

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Authors: Mukesh R. Goswami

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Sports Competition Anxiety test (SCAT) constructed and standardized by Martens was Administrated on 30 National level (15 male, 15 female) Volleyball players of Gujarat. The age of subjects ranged between 19 to 22 years. The purpose of the study was to compare the level of Anxiety between male and female national level Volleyball players of Gujarat. Statistical analysis has been done by T-test and the significance of the result was seen on 0.05 level. The t-test showed that there was no significant difference found in mean difference among the male and the female National level Volleyball players in relation to sports competition anxiety.

Keywords: competition, anxiety, male and female volleyball players, sports

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Authors: Emmanuel Okine Neokye Serge Dossou Martin Iniga Bortey Nketia Alabi-Doku

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Fish stock distribution is greatly influenced by oceanographic environmental conditions. Temporal variations of temperature and other oceanic properties, resulting from climate change have been documented to have a strong impact on fisheries and aquaculture. In Ghana, Sardinella species are one of the most important fisheries resources; they constitute about 60% of the total catch of coastal fisheries and are more predominant during the upwelling season. The present study investigated the role of physical oceanographic environmental conditions in the catches of Sardinella species: S. aurita and S. maderensis, which were landed in Ghana. Furthermore, we examined the relationship between environmental conditions and catches of Sardinella species for seasonal and interannual variations between 2005 and 2015. For oceanographic environmental factors, we used comprehensive datasets, which consist of :(1) daily in situ SST data obtained at two coastal stations in Ghana; (i) Cape 3 Points (4.7° N, -2.09° W) and (ii) Tema (5° N, 0° E), for the period 2005–2015, (2) Monthly SST data (MOAA GPV) from JAMSTEC, and (3) gridded 10 metre wind data from CCMP reanalysis. The analysis of the data collected showed that higher (lower) wind velocity forms stronger (weaker) coastal upwelling that is detected by lower (higher) SST, resulting in a higher (lower) catch of Sardinella spp., in both seasonal and interannual variations. It was also observed that the capture ability of small pelagic fish species such as Sardinella spp. is depend on the intensity of the coastal upwelling. Moreso, the Atlantic Meridional Mode index (climatic index) is now known to be a possible factor to the interannual variation in catch of small pelagic fish species.

Keywords: Sardinella spp., fish, climate change, Ghana

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Authors: Ahmed M. Khedr, Saad M. Abdelrahman, Kareem M. Tonbol

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Two geo-referenced sea level datasets (September 2008 – November 2010) and (April 2012 – January 2014) were recorded at Alexandria Western Harbour (AWH). Accurate re-definition of tidal datum, referred to the latest International Terrestrial Reference Frame (ITRF-2014), was discussed and updated to improve our understanding of the old predefined tidal datum at Alexandria. Tidal and non-tidal components of sea level were separated with the use of Delft-3D hydrodynamic model-tide suit (Delft-3D, 2015). Tidal characteristics at AWH were investigated and harmonic analysis showed the most significant 34 constituents with their amplitudes and phases. Tide was identified as semi-diurnal pattern as indicated by a “Form Factor” of 0.24 and 0.25, respectively. Principle tidal datums related to major tidal phenomena were recalculated referred to a meaningful geodetic height datum. The portion of residual energy (surge) out of the total sea level energy was computed for each dataset and found 77% and 72%, respectively. Power spectral density (PSD) showed accurate resolvability in high band (1–6) cycle/days for the nominated independent constituents, except some neighbouring constituents, which are too close in frequency. Wind and atmospheric pressure data, during the recorded sea level time, were analysed and cross-correlated with the surge signals. Moderate association between surge and wind and atmospheric pressure data were obtained. In addition, long-term sea level rise trend at AWH was computed and showed good agreement with earlier estimated rates.

Keywords: Alexandria, Delft-3D, Egypt, geodetic reference, harmonic analysis, sea level

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Authors: Vijaya

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This paper reports the results of a study that measures the level of receptive vocabularies using the Peabody Picture Vocabulary Test (PPVT) in an ESL context. PPVT is a popular standardized test used to measure the vocabulary level of L1 learners. In this study, PPVT was administered to fourteen 9 to 11 year old Indian ESL learners from the fifth standard from a school in Hyderabad. Their performance is compared with the age appropriate performance of L1 learners. Their performance on noun versus verb items is also compared. The results are discussed concerning the learning goals set by the National Council for Educational Research and Training (NCERT) position paper on Teaching of English in India.

Keywords: national council for educational research and training, India, PPVT, second language acquistion, vocabulary acquisition

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Authors: Barry Hojjatie

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Uniaxial (e.g., three-point bending) and biaxial flexure tests are used frequently for determining the strength of ceramics. It is generally believed that the biaxial test has an advantage as compared to uniaxial test because it produces a state of pure tension on the lower surface of the specimen and the maximum tensile stress, which is usually responsible for crack initiation and failure is unaffected by the edge condition. However, inconsistent strength values have been reported for the same material and testing conditions. The objective of this study was to analyze the strength of dental porcelain materials using the two different test methods and evaluate the main contributions to variability in biaxial testing and to analyze the relative influence of variables such as specimen geometric conditions and loading conditions on calculated strength of porcelain subjected to biaxial testing. Porcelain disks (16 mm dia x 2 mm thick) were subjected to biaxial flexure (pin-on-three-ball), and flexure strength values were calculated. A 3-D finite element model was developed to simulate various biaxial flexure test conditions. Stresses were analyzed for ceramic thickness in the range of 1.0-3.0 mm. For a 2-mm-thick disk subjected to a point load of 200 N, the maximum tensile stress at the lower surface was 180 MPa. This stress decreased to 95, 77, 68, and 59 MPa for the radius of the load values of 0.15, 0.3, 0.6, and 1.0 mm, respectively. Tensile stresses which developed at the top surface near the site of loading were small for the radius of the load ≥ 0.6 mm.

Keywords: ceramis, biaxial, flexure test, uniaxial

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Authors: M. A. Hernández-Ceballos, E. G. San Miguel, C. Galán, J. P. Bolívar

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The evolution of 7Be and 210Pb activity concentrations in surface air along the Guadalquivir valley (southern Iberian Peninsula) is presented in this study. Samples collected for 48 h, every fifteen days, from September 2012 to November 2013 at two sampling sites (Huelva city in the mouth and Cordoba city in the middle (located 250 km far away)), are used to 1) analysing the spatial variability and 2) understanding the influence of wind conditions on 7Be and 210Pb. Similar average concentrations were registered along the valley. The mean 7Be activity concentration was 4.46 ± 0.21 mBq/m3 at Huelva and 4.33 ± 0.20 mBq/m3 at Cordoba, although registering higher maximum and minimum values at Cordoba (9.44 mBq/m3 and 1.80 mBq/m3) than at Huelva (7.95 mBq/m3 and 1.04 mBq/m3). No significant differences were observed in the 210Pb mean activity concentrations between Cordoba (0.40 ± 0.04 mBq/m3) and Huelva (0.35 ± 0.04 mBq/m3), although the maximum (1.10 mBq/m3 and 0.87 mBq/m3) and minimum (0.02 mBq/m3 and 0.04 mBq/m3) values were recorded in Cordoba. Although similar average concentrations were obtained in both sites, the temporal evolution of both natural radionuclides presents differences between them. The meteorological analysis of two sampling periods, in which large differences on 7Be and 210Pb concentrations are observed, indicates the different impact of surface and upper wind dynamics. The analysis reveals the different impact of the two sea-land breeze patterns usually observed along the valley (pure and non-pure) and the corresponding air masses at higher layers associated with each one. The pure, with short development (around 30 km inland) and increasing accumulation process, favours high concentrations of both radionuclides in Huelva (coastal site), while the non-pure, with winds sweeping the valley until arrive to Cordoba (250 km far away), causes high activity values at this site. These results reveal the impact of mesoscale conditions on these two natural radionuclides, and the importance of these circulations on its spatial and temporal variability.

Keywords: 7Be, 210Pb, air masses, mesoscale process

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Authors: M. Nghizaderokni, A. Janalizadechobbasty, M. Azizi, M. Naghizaderokni

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The liquefaction resistance of soils can be evaluated using laboratory tests such as cyclic simple shear, cyclic triaxial, cyclic tensional shear, and field methods such as Standard Penetration Test (SPT), Cone Penetration Test (CPT), and Shear Wave Velocity (Vs). This paper outlines a great correlation between shear wave velocity and standard penetration resistance of granular soils was obtained. Using Seeds standard penetration test (SPT) based soil liquefaction charts, new charts of soil liquefaction evaluation based on shear wave velocity data were developed for various magnitude earthquakes.

Keywords: soil, liquefaction, shear wave velocity, standard penetration resistance

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Authors: A. Mohammadi, S. Asghari, M. Aien, M. Rashidinejad

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After emergent of alternative current networks and their popularity, asynchronous motors became more widespread than other kinds of industrial motors. In order to control and run these motors efficiently, an accurate estimation of motor parameters is needed. There are different methods to obtain these parameters such as rotor locked test, no load test, DC test, analytical methods, and so on. The most common drawback of these methods is their inaccuracy in estimation of some motor parameters. In order to remove this concern, a novel method for parameter estimation of induction motors using particle swarm optimization (PSO) algorithm is proposed. In the proposed method, transient state of motor is used for parameter estimation. Comparison of the simulation results purtuined to the PSO algorithm with other available methods justifies the effectiveness of the proposed method.

Keywords: induction motor, motor parameter estimation, PSO algorithm, analytical method

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Authors: Ballout Amor, Yasmina Bouchahm, Lacheheb Dhia Eddine Zakaria

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Several studies all around the world were conducted on the phenomenon of the urban heat island, and referring to the results obtained, one of the most important factors that influence this phenomenon is the mineralization of the cities which means the reducing of evaporative urban surfaces, replacing vegetation and wetlands with concrete and asphalt. The use of vegetation and water can change the urban environment and improve comfort, thus reduce the heat island. The trees act as a mask to the sun, wind, and sound, and also as a source of humidity which reduces air temperature and surrounding surfaces. Water also acts as a buffer to noise; it is also a source of moisture and regulates temperature not to mention the psychological effect on humans. Our main objective in this paper is to determine the impact of vegetation, ponds and fountains on the urban micro climate in general and on the thermal comfort of people along the Independence square in the Algerian city of Sétif, which is a semi-arid climate, in particularly. In order to reach this objective, a comparative study between different scenarios has been done; the use of the Envi-met program enabled us to model the urban environment of the Independence Square and to study the possibility of improving the conditions of comfort by adding an amount of vegetation and water ponds. After studying the results obtained (temperature, relative humidity, wind speed, PMV and PPD indicators), the efficiency of the additions we've made on the square was confirmed and this is what helped us to confirm our assumptions regarding the terms of comfort in the studied site, and in the end we are trying to develop recommendations and solutions which may contribute to improve the conditions for greater comfort in the Independence square.

Keywords: comfort in outer space, urban environment, scenarisation, vegetation, water ponds, public square, simulation

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Authors: Nur Fathin Alia Che Wahab, Thirumulu Ponnuraj Kannan, Zuliani Mahmood, Ismail Ab. Rahman, Hanafi Ismail

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Locally produced Biphasic Calcium Phosphate (BCP) consists of hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) which is a promising material for dentin and bone regeneration as well as in tissue engineering applications. The study was carried out to investigate the mutagenic effect of locally produced BCP using Ames test. Mutagenicity was evaluated with and without the addition of metabolic activation system (S9). This study was performed on Salmonella typhimurium TA98, TA102, TA1537, and TA1538 strains using preincubation assay method. The doses tested were 5000, 2500, 1250, 625, 313 µg/plate. Negative and positive controls were also included. The bacteria were incubated for 48 hours at 37 ± 0.5 °C. Then, the revertant colonies were counted. Data obtained were evaluated using non-statistical method. The mean number of revertant colonies in strains with and without S9 mix treated with locally produced BCP was less than double when compared to negative control for all the tested concentrations. The results from this study indicate that the locally produced BCP is non-mutagenic under the present test conditions.

Keywords: ames test, biphasic calcium phosphate, dentin regeneration, mutagenicity

Procedia PDF Downloads 323

Authors: Hee Yong Kang, Hyeon Ho Shin, Jung Cheol Yoo, Il Taek Lee, Sung Mo Yang

Abstract:

Lightweight technology using composites is being developed for vehicle seat structures, and its design must meet the safety requirements. According to the Federal Motor Vehicle Safety Standard (FMVSS) 207 seating systems test procedure, the back moment load is applied to the seat back frame structure for the safety evaluation of the vehicle seat. The seat back frame using the composites is divided into three parts: upper part frame, and left- and right-side frame parts following the manufacturing process. When a rear moment load is applied to the seat back frame, the side frame receives the bending load and the torsional load at the same time. This results in the largest loaded strength. Therefore, strength test of the component unit is required. In this study, a component test method based on the FMVSS 207 seating systems test procedure was proposed for the strength analysis of bending load and torsional load of the automotive Bulk Molding Compound (BMC) Seat Back Side Frame. Moreover, strength evaluation according to the carbon band reinforcement was performed. The back-side frame parts of the seat that are applied to the test were manufactured through BMC that is composed of vinyl ester Matrix and short carbon fiber. Then, two kinds of reinforced and non-reinforced parts of carbon band were formed through a high-temperature compression molding process. In addition, the structure that is applied to the component test was constructed by referring to the FMVSS 207. Then, the bending load and the torsional load were applied through the displacement control to perform the strength test for four load conditions. The results of each test are shown through the load-displacement curves of the specimen. The failure strength of the parts caused by the reinforcement of the carbon band was analyzed. Additionally, the fracture characteristics of the parts for four strength tests were evaluated, and the weakness structure of the back-side frame of the seat structure was confirmed according to the test conditions. Through the bending and torsional strength test methods, we confirmed the strength and fracture characteristics of BMC Seat Back Side Frame according to the carbon band reinforcement. And we proposed a method of testing the part strength of a seat back frame for vehicles that can meet the FMVSS 207.

Keywords: seat back frame, bending and torsional strength, BMC (Bulk Molding Compound), FMVSS 207 seating systems

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Authors: Zeinab Gharibi, B. Stoevesandt, J. Peinke

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Long term surface erosion of wind turbine blades, especially at the leading edge, impairs aerodynamic performance; therefore, lowers efficiency of the blades mostly in the high-speed rotor tip regions. Blade protection provides significant improvements in annual energy production, reduces costly downtime, and protects the integrity of the blades. However, this protection still influences the aerodynamic behavior, and broadband noise caused by interaction between the impinging turbulence and blade’s leading edge. This paper presents an extensive numerical aeroacoustics approach by investigating the sound power spectra of the eroded and coated NACA 64-618 wind turbine airfoil and evaluates aeroacoustics improvements after the protection procedure. Using computational fluid dynamics (CFD), different quasi 2D numerical grids were implemented and special attention was paid to the refinement of the boundary layers. The noise sources were captured and decoupled with acoustic propagation via the derived formulation of Curle’s analogy implemented in OpenFOAM. Therefore, the noise spectra were compared for clean, coated and eroded profiles in the range of chord-based Reynolds number (1.6e6 ≤ Re ≤ 11.5e6). Angle of attack was zero in all cases. Verifications were conducted for the clean profile using available experimental data. Sensitivity studies for the far-field were done on different observational positions. Furthermore, beamforming studies were done simulating an Archimedean spiral microphone array for far-field noise directivity patterns. Comparing the noise spectra of the coated and eroded geometries, results show that, coating clearly improves aerodynamic and acoustic performance of the eroded airfoil.

Keywords: computational fluid dynamics, computational aeroacoustics, leading edge, OpenFOAM

Procedia PDF Downloads 223

Authors: Ojas Chaudhari, Ali Nejad Ghafar, Giedrius Zirgulis, Marjan Mousavi, Tommy Ellison, Sandra Pousette, Patrick Fontana

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In Swedish tunnel construction, a critical issue that has been repeatedly acknowledged is corrosion and, consequently, failure of the rock bolts in rock support systems. The defective installation of rock bolts results in the formation of cavities in the cement mortar that is regularly used to fill the area under the dome plates. These voids allow for water-ingress to the rock bolt assembly, which results in corrosion of rock bolt components and eventually failure. In addition, the current installation technique consists of several manual steps with intense labor works that are usually done in uncomfortable and exhausting conditions, e.g., under the roof of the tunnels. Such intense tasks also lead to a considerable waste of materials and execution errors. Moreover, adequate quality control of the execution is hardly possible with the current technique. To overcome these issues, a non-shrinking/expansive cement-based mortar filled in the paper packaging has been developed in this study which properly fills the area under the dome plates without or with the least remaining cavities, ultimately that diminishes the potential of corrosion. This article summarizes the development process and the experimental evaluation of this technique for the installation of rock bolts. In the development process, the cementitious mortar was first developed using specific cement and shrinkage reducing/expansive additives. The mechanical and flow properties of the mortar were then evaluated using compressive strength, density, and slump flow measurement methods. In addition, isothermal calorimetry and shrinkage/expansion measurements were used to elucidate the hydration and durability attributes of the mortar. After obtaining the desired properties in both fresh and hardened conditions, the developed dry mortar was filled in specific permeable paper packaging and then submerged in water bath for specific intervals before the installation. The tests were enhanced progressively by optimizing different parameters such as shape and size of the packaging, characteristics of the paper used, immersion time in water and even some minor characteristics of the mortar. Finally, the developed prototype was tested in a lab-scale rock bolt assembly with various angles to analyze the efficiency of the method in real life scenario. The results showed that the new technique improves the performance of the rock bolts by reducing the material wastage, improving environmental performance, facilitating and accelerating the labor works, and finally enhancing the durability of the whole system. Accordingly, this approach provides an efficient alternative for the traditional way of tunnel bolt installation with considerable advantages for the Swedish tunneling industry.

Keywords: corrosion, durability, mortar, rock bolt

Procedia PDF Downloads 112

Authors: Sung-Uk Wee, Chang-Sung Seok, Jae-Mean Koo, Jeong-Min Lee

Abstract:

Gas turbine blade is important part of power plant, so it is necessary to evaluate gas turbine reliability. For better heat efficiency, inlet temperature of gas turbine has been elevated more and more so gas turbine blade is exposed to high-temperature environment. Then, higher inlet temperature affects mechanical behavior of the gas turbine blade, so it is necessary that evaluation of mechanical property of gas turbine blade at high-temperature environment. In this study, tensile test and fatigue test were performed at various high temperature, and fatigue life was predicted by Coffin-Manson equation at each temperature. The experimental results showed that gas turbine blade has a lower elastic modulus and shorter fatigue life at higher temperature.

Keywords: gas turbine blade, tensile test, fatigue life, stress-strain

Procedia PDF Downloads 477

Authors: Md. Rezaul Karim, Md. Ashikur Rahman, Dewan Mahmud Mim

Abstract:

Scarcity of potable water as the result of rapid climate change and saltwater intrusion in groundwater has been a major problem in the coastal regions over the world. In equinoctial countries like Bangladesh, where sunlight is available for more than 10 hours a day, Solar Distillation provides a promising sustainable way for safe drinking water supply in coastal poor households with negligible major cost and difficulty of construction and maintenance. In this paper, two passive type solar stills- a Conventional Single Slope Solar still (CSS) and a Pyramid Solar Sill (PSS) is used and relationship is established between distill water output corresponding to four different factors- temperature, solar intensity, relative humidity and wind speed for Gazipur, Bangladesh. Comparison is analyzed between the two different still outputs for nine months period (January- September) and efficiency is calculated. Later a thermal mathematical model is developed and the distilled water output for Khulna, Bangladesh is computed. Again, difference between the output of the two cities- Gazipur and Khulna is demonstrated and finally an economic analysis is prepared. The distillation output has a positive correlation with temperature and solar intensity, inverse relation with relative humidity and wind speed has nugatory consequence. The maximum output of Conventional Solar Still is obtained 3.8 L/m2/day and Pyramid still is 4.3 L/m2/day for Gazipur and almost 15% more efficiency is found for Pyramid still. Productivity in Khulna is found almost 20% more than Gazipur. Based on economic analysis, taking 10 BDT, per liter, the net profit, benefit cost ratio, payback period all indicates that both stills are feasible but pyramid still is more feasible than Conventional Still. Finally, for a 3-4 member family, area of 4 m2 is suggested for Conventional Still and 3m2 for Pyramid Solar Still.

Keywords: solar distillation, household water supply, saline zones, Bangladesh

Procedia PDF Downloads 271

Authors: Esmat Momeni, Shabnam Basari, Mohammad Beheshtinia

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The purpose of this study is to provide a symbolic explanation of the four elements in Zoroastrianism and sustainable ecosystems with an ecological approach. The research method is fundamental and deductive content analysis. Data collection has been done through library and documentary methods and through reading books and related articles. The population and sample of the present study are Yazd city and Iran country after discovering symbolic concepts derived from the theoretical foundations of Zoroastrianism in four elements of water, air, soil, fire and conformity with Iranian architecture with the ecological approach in Yazd city, the sustainable ecosystem it is explained by the system of nature. The validity and reliability of the results are based on the trust and confidence of the research literature. Research findings show that Yazd was one of the bases of Zoroastrianism in Iran. Many believe that the first person to discuss the elements of nature and respect Zoroastrians is the Prophet of this religion. Keeping the environment clean and pure by paying attention to and respecting these four elements. The water element is a symbol of existence in Zoroastrianism, so the people of Yazd used the aqueduct and designed a pool in front of the building. The soil element is a symbol of the raw material of human creation in the Zoroastrian religion, the most readily available material in the desert areas of Yazd, used as bricks and adobes, creating one of the most magnificent roof coverings is the dome. The wind element represents the invisible force of the soul in Creation in Zoroastrianism, the most important application of wind in the windy, which is a highly efficient cooling system. The element of fire, which is always a symbol of purity in Zoroastrianism, is located in a special place in Yazd's Ataskadeh (altar/ temple), where the most important religious prayers are held in and against the fire. Consequently, indigenous knowledge and attention to indigenous architecture is a part of the national capital of each nation that encompasses their beliefs, values, methods, and knowledge. According to studies on the four elements of Zoroastrianism, the link between these four elements are that due to the hot and dry fire at the beginning, it is the fire that begins to follow the nature of the movement in the stillness of the earth, and arises from the heat of the fire and because of vigor and its decreases, cold (wind) emerges, and from cold, humidity and wetness. And by examining books and resources on Yazd's architectural design with an ecological approach to the values of the four elements Zoroastrianism has been inspired, it can be concluded that in order to have environmentally friendly architecture, it is essential to use sustainable architectural principles, to link religious and sacrament culture and ecology through architecture.

Keywords: ecology, architecture, quadruple elements of air, soil, water, fire, Zoroastrian religion, sustainable ecosystem, Iran, Yazd city

Procedia PDF Downloads 116

Authors: Gisele C. A. Martins, Leonardo A. Marcolin, Laurenn B. de Macedo, Francisco A. Rocco Lahr, Carlito Calil Jr

Abstract:

The use and development of wood composite materials increased in the past few years. However, in Brazil there are some restrictions on these products regarding their use since it could be considered a potential risk in a fire situation. Thus, becomes evident the need for research aiming to fit these in safety standards. This study aims to evaluate the efficiency of two new fire retardant products produced by a Brazilian industry. Tests were performed on plywood panels of Pinus spp previously immersed, varying the products concentrations and compared with untreated samples. The test used to evaluate the flame spread in a panel was the modified Schlyter test. The product in question was proved efficient, before and after shutting off the burner. Comparing panels with the panels without treatment, there was a decrease of 400% of the height of the flame spread on the treated ones.

Keywords: fire retardant, flame spread, plywood, wood-based material

Procedia PDF Downloads 435