Search results for: diffusion coefficient

Authors: Aschalew Cherie Workneh, K. S. Hari Prasad, Chandra Shekhar Prasad Ojha

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Due to the increase in water scarcity, the crop water stress index (CWSI) is receiving significant attention these days, especially in arid and semiarid regions, for quantifying water stress and effective irrigation scheduling. Nowadays, machine learning techniques such as neural networks are being widely used to determine CWSI. In the present study, the performance of two artificial neural networks, namely, Self-Organizing Maps (SOM) and Feed Forward-Back Propagation Artificial Neural Networks (FF-BP-ANN), are compared while determining the CWSI of rice crop. Irrigation field experiments with varying degrees of irrigation were conducted at the irrigation field laboratory of the Indian Institute of Technology, Roorkee, during the growing season of the rice crop. The CWSI of rice was computed empirically by measuring key meteorological variables (relative humidity, air temperature, wind speed, and canopy temperature) and crop parameters (crop height and root depth). The empirically computed CWSI was compared with SOM and FF-BP-ANN predicted CWSI. The upper and lower CWSI baselines are computed using multiple regression analysis. The regression analysis showed that the lower CWSI baseline for rice is a function of crop height (h), air vapor pressure deficit (AVPD), and wind speed (u), whereas the upper CWSI baseline is a function of crop height (h) and wind speed (u). The performance of SOM and FF-BP-ANN were compared by computing Nash-Sutcliffe efficiency (NSE), index of agreement (d), root mean squared error (RMSE), and coefficient of correlation (R²). It is found that FF-BP-ANN performs better than SOM while predicting the CWSI of rice crops.

Keywords: artificial neural networks; crop water stress index; canopy temperature, prediction capability

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Authors: Yan Ping Chen, Hau Yin Chung

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The Ideal Profile Method (IPM) is a newly developed descriptive sensory analysis conducted by consumers without previous training. To perform this test, both the perceived and the ideal intensities from the judgements of consumers on products’ attributes, as well as their hedonic ratings were collected for formulating an ideal product (the most liked one). In addition, Ideal Profile Analysis (IPA) was conducted to check the consistency of the ideal data at both the panel and consumer levels. In this test, 12 commercial plain sufus bought from Hong Kong local market were tested by 113 consumers according to the IPM, and rated on 22 attributes. Principal component analysis was used to profile the perceived and the ideal spaces of tested products. The consistency of ideal data was then checked by IPA. The result showed that most consumers shared a common ideal. It was observed that the sensory product space and the ideal product space were structurally similar. Their first dimensions all opposed products with intense fermented related aroma to products with less fermented related aroma. And the predicted ideal profile (the estimated liking score around 7.0 in a 9.0-point scale) got higher hedonic score than the tested products (the average liking score around 6.0 in a 9.0-point scale). For the majority of consumers (95.2%), the stated ideal product considered as a potential ideal through checking the R2 coefficient value. Among all the tested products, sample-6 was the most popular one with consumer liking percentage around 30%. This product with less fermented and moldy flavour but easier to melt in mouth texture possessed close sensory profile according to the ideal product. This experiment validated that data from untrained consumers could be guided as useful information. Appreciated sensory characteristics could be served as reference in the optimization of the commercial plain sufu.

Keywords: ideal profile method, product development, sensory evaluation, sufu (fermented soybean curd)

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Authors: Folasade R. Sulaiman

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Pupils’ health and nutrition are basically important to their schooling. The preponderance of avoidable deaths among children in Africa (WHO, 2000) may not be unconnected with the nutritional and health education status of families and communities that have their children as school clients. This study adopted a descriptive survey design focusing on the assessment of the level of nutritional and health education of families and community members in the rural riverine areas of Ogun State. Two research questions were raised. The Nutritional and Health Education of Families and Communities Inventory (NHEFCI) was used to collect data from 250 rural child-bearing aged women, and 0.73 test-retest reliability coefficient was established to determine the strength of the instrument. Data collected were analysed using descriptive statistics of frequency counts, percentages and mean in accordance with research questions raised in the study. The findings revealed amongst others: that 65% of the respondents had low level of nutritional and health education among the families and community members; while 72% had low level of awareness of the possible influence of nutritional and health education on the learning outcomes of the children. Based on the findings, it was recommended among others that government should intensify efforts on sensitization, mass literacy campaign etc.; also improve upon the already existing School Feeding Programme in Nigerian primary schools to provide at least one balanced diet for children while in school; community health workers, social workers, Non-Governmental Organizations (NGO) should collaborate with international Organizations like UNICEF, UNESCO, WHO etc. to organize sensitization programmes for members of the rural riverine communities on the importance of meeting the health and nutritional needs of their children in order to attain their educational potentials.

Keywords: nutritional and health education, learning capacities, school-age children, universal basic education, rural riverine areas

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Authors: B. L. Gadiga

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This study assesses the major ecological zones in Nigeria with the view to understanding the spatial pattern of vegetation zones and the implications on conservation within the period of sixteen (16) years. Satellite images used for this study were acquired from the SPOT-VEGETATION between 1998 and 2013. The annual NDVI images selected for this study were derived from SPOT-4 sensor and were acquired within the same season (November) in order to reduce differences in spectral reflectance due to seasonal variations. The images were sliced into five classes based on literatures and knowledge of the area (i.e. <0.16 Non-Vegetated areas; 0.16-0.22 Sahel Savannah; 0.22-0.40 Sudan Savannah, 0.40-0.47 Guinea Savannah and >0.47 Forest Zone). Classification of the 1998 and 2013 images into forested and non forested areas showed that forested area decrease from 511,691 km² in 1998 to 478,360 km² in 2013. Differencing change detection method was performed on 1998 and 2013 NDVI images to identify areas of ecological concern. The result shows that areas undergoing vegetation degradation covers an area of 73,062 km² while areas witnessing some form restoration cover an area of 86,315 km². The result also shows that there is a weak correlation between rainfall and the vegetation zones. The non-vegetated areas have a correlation coefficient (r) of 0.0088, Sahel Savannah belt 0.1988, Sudan Savannah belt -0.3343, Guinea Savannah belt 0.0328 and Forest belt 0.2635. The low correlation can be associated with the encroachment of the Sudan Savannah belt into the forest belt of South-eastern part of the country as revealed by the image analysis. The degradation of the forest vegetation is therefore responsible for the serious erosion problems witnessed in the South-east. The study recommends constant monitoring of vegetation and strict enforcement of environmental laws in the country.

Keywords: vegetation, NDVI, SPOT-vegetation, ecology, degradation

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Authors: Shenghong Huang, Weirong Wang, Xisheng Luo, Xinzhu Li, Xinwen Zhao

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Understanding of material mixing induced by Richtmyer-Meshkov instability (RMI) at extreme shock compressing conditions (high energy density environment: P >> 100GPa, T >> 10000k) is of great significance in engineering and science, such as inertial confinement fusion(ICF), supersonic combustion, etc. Turbulent mixing induced by RMI is a kind of complex fluid dynamics, which is closely related with hydrodynamic conditions, thermodynamic states, material physical properties such as compressibility, strength, surface tension and viscosity, etc. as well as initial perturbation on interface. For phenomena in ordinary thermodynamic conditions (low energy density environment), many investigations have been conducted and many progresses have been reported, while for mixing in extreme thermodynamic conditions, the evolution may be very different due to ionization as well as large difference of material physical properties, which is full of scientific problems and academic interests. In this investigation, the first principle based molecular dynamic method is applied to study metal Lithium and gas Hydrogen (Li-H2) interface mixing in micro/meso scale regime at different shock compressing loading speed ranging from 3 km/s to 30 km/s. It's found that, 1) Different from low-speed shock compressing cases, in high-speed shock compresing (>9km/s) cases, a strong acceleration of metal/gas interface after strong shock compression is observed numerically, leading to a strong phase inverse and spike growing with a relative larger linear rate. And more specially, the spike growing rate is observed to be increased with shock loading speed, presenting large discrepancy with available empirical RMI models; 2) Ionization is happened in shock font zone at high-speed loading cases(>9km/s). An additional local electric field induced by the inhomogeneous diffusion of electrons and nuclei after shock font is observed to occur near the metal/gas interface, leading to a large acceleration of nuclei in this zone; 3) In conclusion, the work of additional electric field contributes to a mechanism of RMI in micro/meso scale regime at extreme shock compressing conditions, i.e., a Rayleigh-Taylor instability(RTI) is induced by additional electric field during RMI mixing process and thus a larger linear growing rate of interface spike.

Keywords: ionization, micro/meso scale, material mixing, shock

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Authors: Maryam Kheirollahpour, Mahmoud Danaee, Amir Faisal Merican, Asma Ahmad Shariff

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Background: The presence of nonlinearity among the risk factors of eating behavior causes a bias in the prediction models. The accuracy of estimation of eating behaviors risk factors in the primary prevention of obesity has been established. Objective: The aim of this study was to explore the potential of a hybrid model of structural equation modeling (SEM) and Artificial Neural Networks (ANN) to predict eating behaviors. Methods: The Partial Least Square-SEM (PLS-SEM) and a hybrid model (SEM-Artificial Neural Networks (SEM-ANN)) were applied to evaluate the factors affecting eating behavior patterns among university students. 340 university students participated in this study. The PLS-SEM analysis was used to check the effect of emotional eating scale (EES), body shape concern (BSC), and body appreciation scale (BAS) on different categories of eating behavior patterns (EBP). Then, the hybrid model was conducted using multilayer perceptron (MLP) with feedforward network topology. Moreover, Levenberg-Marquardt, which is a supervised learning model, was applied as a learning method for MLP training. The Tangent/sigmoid function was used for the input layer while the linear function applied for the output layer. The coefficient of determination (R²) and mean square error (MSE) was calculated. Results: It was proved that the hybrid model was superior to PLS-SEM methods. Using hybrid model, the optimal network happened at MPLP 3-17-8, while the R² of the model was increased by 27%, while, the MSE was decreased by 9.6%. Moreover, it was found that which one of these factors have significantly affected on healthy and unhealthy eating behavior patterns. The p-value was reported to be less than 0.01 for most of the paths. Conclusion/Importance: Thus, a hybrid approach could be suggested as a significant methodological contribution from a statistical standpoint, and it can be implemented as software to be able to predict models with the highest accuracy.

Keywords: hybrid model, structural equation modeling, artificial neural networks, eating behavior patterns

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Authors: Kathryn Strachan, Sameer Otoom, Amal AL-Gallaf, Ahmed Al Ansari

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Introduction: Introducing a reliable method to select graduates for an award in higher education can be challenging but is not impossible. Multisource feedback (MSF) is a popular assessment tool that relies on evaluations of different groups of people, including physicians and non-physicians. It is useful for assessing several domains, including professionalism, communication and collaboration and may be useful for selecting the best interns to receive a University award. Methods: 16 graduates responded to an invitation to participate in the student award, which was conducted by the Royal College of Surgeons of Ireland-Bahrain Medical University of Bahrain (RCSI Bahrain) using the MSF process. Five individuals from the following categories rated each participant: physicians, nurses, and fellow students. RCSI Bahrain graduates were assessed in the following domains; professionalism, communication, and collaboration. Mean and standard deviation were calculated and the award was given to the graduate who scored the highest among his/her colleagues. Cronbach’s coefficient was used to determine the questionnaire’s internal consistency and reliability. Factor analysis was conducted to examine for the construct validity. Results: 16 graduates participated in the RCSI-Bahrain interns’ award based on the MSF process, giving us a 16.5% response rate. The instrument was found to be suitable for factor analysis and showed 3 factor solutions representing 79.3% of the total variance. Reliability analysis using Cronbach’s α reliability of internal consistency indicated that the full scale of the instrument had high internal consistency (Cronbach’s α 0.98). Conclusion: This study found the MSF process to be reliable and valid for selecting the best graduates for the interns’ awards. However, the low response rates may suggest that the process is not feasible for allowing the majority of the students to participate in the selection process. Further research studies may be required to support the feasibility of the MSF process in selecting graduates for the university award.

Keywords: MSF, RCSI, validity, Bahrain

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Authors: Ami Okabe, Daisuke Gondo, Akira Ogawa, Yasuhisa Hasegawa, Koichi Sato, Sadao Araki, Hideki Yamamoto

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Membrane separation draws attention as the energy-saving technology. Pervaporation (PV) uses hydrophobic ceramic membranes to separate organic compounds from industrial wastewaters. PV makes it possible to separate organic compounds from azeotropic mixtures and from aqueous solutions. For the PV separation of low concentrations of organics from aqueous solutions, hydrophobic ceramic membranes are expected to have high separation performance compared with that of conventional hydrophilic membranes. Membrane separation performance is evaluated based on the pervaporation separation index (PSI), which depends on both the separation factor and the permeate flux. Ingenuity is required to increase the PSI such that the permeate flux increases without reducing the separation factor or to increase the separation factor without reducing the flux. A thin separation layer without defects and pinholes is required. In addition, it is known that the flux can be increased without reducing the separation factor by reducing the diffusion resistance of the membrane support. In a previous study, we prepared hydrophobic silica membranes by a molecular templating sol−gel method using cetyltrimethylammonium bromide (CTAB) to form pores suitable for permitting the passage of organic compounds through the membrane. We separated low-concentration organics from aqueous solutions by PV using these membranes. In the present study, hydrophobic silica membranes were prepared on a porous alumina hollow fiber support that is thinner than the previously used alumina support. Ethyl acetate (EA) is used in large industrial quantities, so it was selected as the organic substance to be separated. Hydrophobic silica membranes were prepared by dip-coating porous alumina supports with a -alumina interlayer into a silica sol containing CTAB and vinyltrimethoxysilane (VTMS) as the silica precursor. Membrane thickness increases with the lifting speed of the sol in the dip-coating process. Different thicknesses of the γ-alumina layer were prepared by dip-coating the support into a boehmite sol at different lifting speeds (0.5, 1, 3, and 5 mm s-1). Silica layers were subsequently formed by dip-coating using an immersion time of 60 s and lifting speed of 1 mm s-1. PV measurements of the EA (5 wt.%)/water system were carried out using VTMS hydrophobic silica membranes prepared on -alumina layers of different thicknesses. Water and EA flux showed substantially constant value despite of the change of the lifting speed to form the γ-alumina interlayer. All prepared hydrophobic silica membranes showed the higher PSI compared with the hydrophobic membranes using the previous alumina support of hollow fiber.

Keywords: membrane separation, pervaporation, hydrophobic, silica

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Authors: John Odo Ogah

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The study investigated ways of fostering students’ interest in senior secondary two Biology, using prior knowledge of behavioural objectives and assertive questioning strategies in Benue State of Nigeria. A quasi-experimental research design was adopted; the population comprised 8,571 senior Secondary two students. The sample consisted of 265 SSII biology students selected from six government schools in the study area using a multi-staged sampling technique. Data was generated using the Biology Interest Inventory (BII). The instrument was validated and subjected to reliability analysis using Cronbach’s Alpha formula, which yielded a coefficient of 0.73. Three research questions guided the study, while three hypotheses were formulated and tested. Data collected were analyzed using means, bar graphs, and standard deviations to answer the research questions, while analysis of covariance (ANCOVA) was employed in testing the hypotheses at 0.05 level of significance. The finding revealed that there is a significant difference in the mean interest ratings of students taught cellular respiration and excretory system using assertive questioning strategy, prior knowledge of behavioural objectives strategy and lecture method (p=0.000˂0.05). There is no significant difference in the mean interest ratings of male and female students taught cellular respiration and excretory systems using an assertive questioning strategy (p=0.790>0.05). There is significant difference in the mean interest ratings of male and female students taught cellular respiration and execratory system using prior knowledge of behavioural objectives strategy (p=0.028˂0.05). It was recommended, among others, that teachers should endeavor to utilize prior knowledge of behavioral objectives strategy in teaching biology in order to harness its benefits as it enhances students’ interest.

Keywords: interest, assertive, questioning, prior, knowledge

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Authors: Jernice S. Y. Tan

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Introduction: Reliability within and between testers is vital to ensure the accuracy of any motor assessment instrument. However, reliability checks of the Movement Assessment Battery for Children-2 (MABC-2) age band 3 using multiple testers assigned to different MABC-2 tasks for the same group of participants are uncommon. Multiple testers were not stated as a choice in the MABC-2 manual. Therefore, the purpose of this study was to determine the inter- and intra-tester reliability for using multiple testers to administer the test protocols of MABC-2 age band 3. Methods: Thirty volunteered adolescents (n = 30; 15 males, 15 females; age range: 13 – 16 years) performed the eight tasks in a randomised sequence at three different test stations for the MABC-2 task components (Manual Dexterity, Aiming and Catching, Balance). Ethics approval and parental consent were obtained. The participants were videotaped while performing the test protocols of MABC-2 age band 3. Five testers were involved in the data collection process. They were Sports Science graduating students doing their final year project and were supervised by experienced motor assessor. Inter- and intra-tester reliability checks using intra-class coefficient (ICC) were carried out using the videotaped data. Results: The inter-tester reliability between the five testers for the eight tasks ranged from rᵢcc = 0.705 to rᵢcc = 0.995. This suggests that the average agreement between them was considered good to excellent. With the exception of one tester who had rᵢcc = 0.687 for one of the eight tasks (i.e. zip-zap hopping), the intra-tester reliability within each tester ranged from rᵢcc = 0.728 to rᵢcc = 1.000, and this also suggested good to excellent consistency within testers. Discussion: The use of multiple testers with good intra-tester reliability for different test stations is feasible. This method allows several participants to be assessed concurrently at different test stations and saves overall data collection time. Therefore, it is recommended that the administering of MABC-2 with multiple testers should be extended to other age bands ensuring the feasibility of such method for other age bands.

Keywords: adolescents, MABC, motor assessment, motor skills, reliability

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Authors: Jasbir Arora, Indu Talwar, Daisy Sahni, Vidya Rattan

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Introduction: Age estimation is a crucial step to build the identity of a person, both in case of deceased and alive. In adults, age can be estimated on the basis of six regressive (Attrition, Secondary dentine, Dentine transparency, Root resorption, Cementum apposition and Periodontal Disease) changes in teeth qualitatively using scoring system and quantitatively by micrometric method. The present research was designed to establish the reliability of qualitative (method 1) and quantitative (method 2) of age estimation among North Indians and to compare the efficacy of these two methods. Method: 250 single-rooted extracted teeth (18-75 yrs.) were collected from Department of Oral Health Sciences, PGIMER, Chandigarh. Before extraction, periodontal score of each tooth was noted. Labiolingual sections were prepared and examined under light microscope for regressive changes. Each parameter was scored using Gustafson’s 0-3 point score system (qualitative), and total score was calculated. For quantitative method, each regressive change was measured quantitatively in form of 18 micrometric parameters under microscope with the help of measuring eyepiece. Age was estimated using linear and multiple regression analysis in Gustafson’s method and Kedici’s method respectively. Estimated age was compared with actual age on the basis of absolute mean error. Results: In pooled data, by Gustafson’s method, significant correlation (r= 0.8) was observed between total score and actual age. Total score generated an absolute mean error of ±7.8 years. Whereas, for Kedici’s method, a value of correlation coefficient of r=0.5 (p<0.01) was observed between all the eighteen micrometric parameters and known age. Using multiple regression equation, age was estimated, and an absolute mean error of age was found to be ±12.18 years. Conclusion: Gustafson’s (qualitative) method was found to be a better predictor for age estimation among North Indians.

Keywords: forensic odontology, age estimation, North India, teeth

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Authors: Younes El Khchine, Mohammed Sriti

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A parametric study has been conducted to analyse the flow around S809 airfoil of a wind turbine in order to better understand the characteristics and effects of laminar separation bubble (LSB) on aerodynamic design for maximizing wind turbine efficiency. Numerical simulations were performed at low Reynolds numbers by solving the Unsteady Reynolds Averaged Navier-Stokes (URANS) equations based on C-type structural mesh and using the γ-Reθt turbulence model. A two-dimensional study was conducted for the chord Reynolds number of 1×10⁵ and angles of attack (AoA) between 0 and 20.15 degrees. The simulation results obtained for the aerodynamic coefficients at various angles of attack (AoA) were compared with XFoil results. A sensitivity study was performed to examine the effects of Reynolds number and free-stream turbulence intensity on the location and length of the laminar separation bubble and the aerodynamic performances of wind turbines. The results show that increasing the Reynolds number leads to a delay in the laminar separation on the upper surface of the airfoil. The increase in Reynolds number leads to an accelerated transition process, and the turbulent reattachment point moves closer to the leading edge owing to an earlier reattachment of the turbulent shear layer. This leads to a considerable reduction in the length of the separation bubble as the Reynolds number is increased. The increase in the level of free-stream turbulence intensity leads to a decrease in separation bubble length and an increase in the lift coefficient while having negligible effects on the stall angle. When the AoA increased, the bubble on the suction airfoil surface was found to move upstream to the leading edge of the airfoil, that causes earlier laminar separation.

Keywords: laminar separation bubble, turbulence intensity, S809 airfoil, transition model, Reynolds number

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Authors: Pouriya Darabiyan, Hadis Nazari, Kourosh Zarea, Saeed Ghanbari, Zeinab Raiesifar, Morteza Khafaie, Hanna Tuvesson

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Introduction Since the beginning of mobile phone addiction, alexithymia, depression, anxiety and stress have been stated as risk factors for Internet addiction, so this study was conducted with the aim of investigating the relationship between Alexithymia and Mobile phone addiction along with the mediating role of anxiety, stress and depression. Materials and methods In this descriptive-analytical and cross-sectional study in 2022, 412 students School of Nursing & Midwifery of Ahvaz Jundishapur University of Medical Sciences were included in the study using available sampling method. Data collection tools were: Demographic Information Questionnaire, Toronto Alexithymia Scale (TAS-20), Depression, Anxiety, Stress Scale (DASS-21) and Mobile Phone Addiction Index (MPAI). Frequency, Pearson correlation coefficient test and linear regression were used to describe and analyze the data. Also, structural equation models and path analysis method were used to investigate the direct and indirect effects as well as the total effect of each dimension of Alexithymia on Mobile phone addiction with the mediating role of stress, depression and anxiety. Statistical analysis was done by SPSS version 22 and Amos version 16 software. Results Alexithymia was a predictive factor for mobile phone addiction. Also, Alexithymia had a positive and significant effect on depression, anxiety and stress. Depression, anxiety and stress had a positive and significant effect on mobile phone addiction. Depression, anxiety and stress variables played the role of a relative mediating variable between Alexithymia and mobile phone addiction. Alexithymia through depression, anxiety and stress also has an indirect effect on Internet addiction. Conclusion Alexithymia is a predictive factor for mobile phone addiction; And the variables of depression, anxiety and stress play the role of a relative mediating variable between Alexithymia and mobile phone addiction.

Keywords: alexithymia, mobile phone, depression, anxiety, stress

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Authors: Siva K. Bathina, Sudheer Siddapureddy

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Pool fires are formed when the flammable liquid accidentally spills on the ground or water and ignites. Pool fire is a kind of buoyancy-driven and diffusion flame. There have been many pool fire accidents caused during processing, handling and storing of liquid fuels in chemical and oil industries. Such kind of accidents causes enormous damage to property as well as the loss of lives. Pool fires are complex in nature due to the strong interaction among the combustion, heat and mass transfers and pyrolysis at the fuel surface. Moreover, the experimental study of such large complex fires involves fire safety issues and difficulties in performing experiments. In the present work, large eddy simulations are performed to study such complex fire scenarios using fire dynamic simulator. A 1 m diesel pool fire is considered for the studied cases, and diesel is chosen as it is most commonly involved fuel in fire accidents. Fire simulations are performed by specifying two different boundary conditions: one the fuel is in liquid state and pyrolysis model is invoked, and the other by assuming the fuel is initially in a vapor state and thereby prescribing the mass loss rate. A domain of size 11.2 m × 11.2 m × 7.28 m with uniform structured grid is chosen for the numerical simulations. Grid sensitivity analysis is performed, and a non-dimensional grid size of 12 corresponding to 8 cm grid size is considered. Flame properties like mass burning rate, irradiance, and time-averaged axial flame temperature profile are predicted. The predicted steady-state mass burning rate is 40 g/s and is within the uncertainty limits of the previously reported experimental data (39.4 g/s). Though the profile of the irradiance at a distance from the fire along the height is somewhat in line with the experimental data and the location of the maximum value of irradiance is shifted to a higher location. This may be due to the lack of sophisticated models for the species transportation along with combustion and radiation in the continuous zone. Furthermore, the axial temperatures are not predicted well (for any of the boundary conditions) in any of the zones. The present study shows that the existing models are not sufficient enough for modeling blended fuels like diesel. The predictions are strongly dependent on the experimental values of the soot yield. Future experiments are necessary for generalizing the soot yield for different fires.

Keywords: burning rate, fire accidents, fire dynamic simulator, pyrolysis

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Authors: Amit Kumar Happy

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This paper is motivated by the importance of multi-sensor image fusion with a specific focus on infrared (IR) and visual image (VI) fusion for various applications, including military reconnaissance. Image fusion can be defined as the process of combining two or more source images into a single composite image with extended information content that improves visual perception or feature extraction. These images can be from different modalities like visible camera & IR thermal imager. While visible images are captured by reflected radiations in the visible spectrum, the thermal images are formed from thermal radiation (infrared) that may be reflected or self-emitted. A digital color camera captures the visible source image, and a thermal infrared camera acquires the thermal source image. In this paper, some image fusion algorithms based upon multi-scale transform (MST) and region-based selection rule with consistency verification have been proposed and presented. This research includes the implementation of the proposed image fusion algorithm in MATLAB along with a comparative analysis to decide the optimum number of levels for MST and the coefficient fusion rule. The results are presented, and several commonly used evaluation metrics are used to assess the suggested method's validity. Experiments show that the proposed approach is capable of producing good fusion results. While deploying our image fusion algorithm approaches, we observe several challenges from the popular image fusion methods. While high computational cost and complex processing steps of image fusion algorithms provide accurate fused results, they also make it hard to become deployed in systems and applications that require a real-time operation, high flexibility, and low computation ability. So, the methods presented in this paper offer good results with minimum time complexity.

Keywords: image fusion, IR thermal imager, multi-sensor, multi-scale transform

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Authors: Archana. S, Usha Rani. G, Anand Balakrishnan, Sanjana.R, Solomon F, Vijayalakshmi. J

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Background: There is evidence that male factors contribute to the infertility of up to 50% of couples, who are evaluated and treated for infertility using advanced assisted reproductive technologies. Genetic abnormalities, including sperm chromosome aneuploidy as well as structural aberrations, are one of the major causes of male infertility. Recent advances in technology expedite the evaluation of sperm aneuploidy. The purpose of the study was to de-termine the prevalence of sperm aneuploidy in infertile males and the degree of association between DNA fragmentation and sperm aneuploidy. Methods: In this study, 75 infertile men were included, and they were divided into four abnormal groups (Oligospermia, Terato-spermia, Asthenospermia and Oligoasthenoteratospermia (OAT)). Men with children who were normozoospermia served as the control group. The Fluorescence in situ hybridization (FISH) method was used to test for sperm aneuploidy, and the Sperm Chromatin Dispersion Assay (SCDA) was used to measure the fragmentation of sperm DNA. Spearman's correla-tion coefficient was used to evaluate the relationship between sperm aneuploidy and sperm DNA fragmentation along with age. P < 0.05 was regarded as significant. Results: 75 partic-ipants' ages varied from 28 to 48 years old (35.5±5.1). The percentage of spermatozoa bear-ing X and Y was determined to be statistically significant (p-value < 0.05) and was found to be 48.92% and 51.18% of CEP X X 1 – nucish (CEP XX 1) [100] and CEP Y X 1 – nucish (CEP Y X 1) [100]. When compared to the rate of DNA fragmentation, it was discovered that infertile males had a greater frequency of sperm aneuploidy. Asthenospermia and OAT groups in sex chromosomal aneuploidy were significantly correlated (p<0.05). Conclusion: Sperm FISH and SCDA assay results showed increased sperm aneuploidy frequency, and DNA fragmentation index in infertile men compared with fertile men. There is a significant relationship observed between sperm aneuploidy and DNA fragmentation in OAT patients. When evaluating male variables and idiopathic infertility, the sperm FISH screening method can be used as a valuable diagnostic tool.

Keywords: ale infertility, dfi (dna fragmentation assay) (scd-sperm chromatin dispersion).art (artificial reproductive technology), trisomy, aneuploidy, fish (fluorescence in-situ hybridization), oat (oligoasthoteratospermia)

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Authors: M. Towhidur Rahman, Nasim Zaman Piyas, M. Sadiqul Baree, Shahnewaz Ahmed

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The design of high-speed craft has recently become one of the most active areas of naval architecture. Speed increase makes these vehicles more efficient and useful for military, economic or leisure purpose. The planing hull is designed specifically to achieve relatively high speed on the surface of the water. Speed on the water surface is closely related to the size of the vessel and the installed power. The Savitsky method was first presented in 1964 for application to non-monohedric hulls and for application to stepped hulls. This method is well known as a reliable comparative to CFD analysis of hull resistance. A computer program based on Savitsky’s method has been developed using MATLAB. The power of high-speed vessels has been computed in this research. At first, the program reads some principal parameters such as displacement, LCG, Speed, Deadrise angle, inclination of thrust line with respect to keel line etc. and calculates the resistance of the hull using empirical planning equations of Savitsky. However, some functions used in the empirical equations are available only in the graphical form, which is not suitable for the automatic computation. We use digital plotting system to extract data from nomogram. As a result, value of wetted length-beam ratio and trim angle can be determined directly from the input of initial variables, which makes the power calculation automated without manually plotting of secondary variables such as p/b and other coefficients and the regression equations of those functions are derived by using data from different charts. Finally, the trim angle, mean wetted length-beam ratio, frictional coefficient, resistance, and power are computed and compared with the results of Savitsky and good agreement has been observed.

Keywords: nomogram, planing hull, principal parameters, regression

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Authors: Younes El Khchine

Abstract:

A parametric study has been conducted to analyse the flow around S809 airfoil of a wind turbine in order to better understand the characteristics and effects of laminar separation bubble (LSB) on aerodynamic design for maximizing wind turbine efficiency. Numerical simulations were performed at low Reynolds numbers by solving the Unsteady Reynolds Averaged Navier-Stokes (URANS) equations based on C-type structural mesh and using the γ-Reθt turbulence model. A two-dimensional study was conducted for the chord Reynolds number of 1×105 and angles of attack (AoA) between 0 and 20.15 degrees. The simulation results obtained for the aerodynamic coefficients at various angles of attack (AoA) were compared with XFoil results. A sensitivity study was performed to examine the effects of Reynolds number and free-stream turbulence intensity on the location and length of the laminar separation bubble and the aerodynamic performances of wind turbines. The results show that increasing the Reynolds number leads to a delay in the laminar separation on the upper surface of the airfoil. The increase in Reynolds number leads to an accelerated transition process, and the turbulent reattachment point moves closer to the leading edge owing to an earlier reattachment of the turbulent shear layer. This leads to a considerable reduction in the length of the separation bubble as the Reynolds number is increased. The increase in the level of free-stream turbulence intensity leads to a decrease in separation bubble length and an increase in the lift coefficient while having negligible effects on the stall angle. When the AoA increased, the bubble on the suction airfoil surface was found to move upstream to the leading edge of the airfoil, causing earlier laminar separation.

Keywords: laminar separation bubble, turbulence intensity, s809 airfoil, transition model, Reynolds number

Procedia PDF Downloads 44

Authors: Spandan Sahu, Amiya Kumar Pati, Kishanjit Kumar Khatua

Abstract:

Vegetation plays a major role in deciding the flow parameters in an open channel. It enhances the aesthetic view of the revetments. The major types of vegetation in river typically comprises of herbs, grasses, weeds, trees, etc. The vegetation in an open channel usually consists of aquatic plants with complete submergence, partial submergence, floating plants. The presence of vegetative plants can have both benefits and problems. The major benefits of aquatic plants are they reduce the soil erosion, which provides the water with a free surface to move on without hindrance. The obvious problems are they retard the flow of water and reduce the hydraulic capacity of the channel. The degree to which the flow parameters are affected depends upon the density of the vegetation, degree of submergence, pattern of vegetation, vegetation species. Vegetation in open channel tends to provide resistance to flow, which in turn provides a background to study the varying trends in flow parameters having vegetative growth in the channel surface. In this paper, an experiment has been conducted on a meandering channel having sinuosity of 1.33 with rigid vegetation cover to investigate the effect on flow parameters, variation of manning’s n with degree of the denseness of vegetation, vegetation pattern and submergence criteria. The measurements have been carried out in four different cross-sections two on trough portion of the meanders, two on the crest portion. In this study, the analytical solution of Shiono and knight (SKM) for lateral distributions of depth-averaged velocity and bed shear stress have been taken into account. Dimensionless eddy viscosity and bed friction have been incorporated to modify the SKM to provide more accurate results. A mathematical model has been formulated to have a comparative analysis with the results obtained from Shiono-Knight Method.

Keywords: bed friction, depth averaged velocity, eddy viscosity, SKM

Procedia PDF Downloads 119

Authors: C. Bolakis, I. S. Karanasiou, D. Grbovic, G. Karunasiri, N. Uzunoglu

Abstract:

A new approach for efficient detection of THz radiation in biomedical imaging applications is proposed. A double-layered absorber consisting of a 32 nm thick aluminum (Al) metallic layer, located on a glass medium (SiO2) of 1 mm thickness, was fabricated and used to design a fine-tuned absorber through a theoretical and finite element modeling process. The results indicate that the proposed low-cost, double-layered absorber can be tuned based on the metal layer sheet resistance and the thickness of various glass media taking advantage of the diversity of the absorption of the metal films in the desired THz domain (6 to 10 THz). It was found that the composite absorber could absorb up to 86% (a percentage exceeding the 50%, previously shown to be the highest achievable when using single thin metal layer) and reflect less than 1% of the incident THz power. This approach will enable monitoring of the transmission coefficient (THz transmission ‘’fingerprint’’) of the biosample with high accuracy, while also making the proposed double-layered absorber a good candidate for a microbolometer pixel’s active element. Based on the aforementioned promising results, a more sophisticated and effective double-layered absorber is under development. The glass medium has been substituted by diluted poly-si and the results were twofold: An absorption factor of 96% was reached and high TCR properties acquired. In addition, a generalization of these results and properties over the active frequency spectrum was achieved. Specifically, through the development of a theoretical equation having as input any arbitrary frequency in the IR spectrum (0.3 to 405.4 THz) and as output the appropriate thickness of the poly-si medium, the double-layered absorber retains the ability to absorb the 96% and reflects less than 1% of the incident power. As a result, through that post-optimization process and the spread spectrum frequency adjustment, the microbolometer detector efficiency could be further improved.

Keywords: bio-imaging, fine-tuned absorber, fingerprint, microbolometer

Procedia PDF Downloads 321

Authors: Suphap Sikkhaphan, Muwanga Zake, Johnnie Wycliffe Frank

Abstract:

The purposes of the study included a) investigating the authentic and transformational leadership model of the directors of tambon health promoting hospitals b) evaluating the relation between the authentic and transformation leadership of the directors of tambon health promoting hospitals and the effectiveness of their hospitals and c) assessing the invariance test of the authentic and transformation leadership of the directors of tambon health promoting hospitals. All 400 southern tambon health promoting hospital directors were enrolled into the study. Half were males (200), and another half were females (200). They were sampled via a stratified method. A research tool was a questionnaire paper containing 4 different sections. The Alpha-Cronbach’s Coefficient was equally to .98. Descriptive analysis was used for demographic data, and inferential statistics was used for the relation and invariance tests of authentic and transformational leadership of the directors of tambon health promoting hospitals. The findings revealed overall the authentic and transformation leadership model of the directors of tambon health promoting hospitals has the relation to the effectiveness of the hospitals. Only the factor of “strong community support” was statistically significantly related to the authentic leadership (p < .05). However, there were four latent variables statistically related to the transformational leadership including, competency and work climate, management system, network cooperation, and strong community support (p = .01). Regarding the relation between the authentic and transformation leadership of the directors of tambon health promoting hospitals and the effectiveness of their hospitals, four casual variables of authentic leadership were not related to those latent variables. In contrast, all four latent variables of transformational leadership has statistically significantly related to the effectiveness of tambon health promoting hospitals (p = .001). Furthermore, only management system variable was significantly related to those casual variables of the authentic leadership (p < .05). Regarding the invariance test, the result found no statistical significance of the authentic and transformational leadership model of the directors of tambon health promoting hospitals, especially between male and female genders (p > .05).

Keywords: authentic leadership, transformational leadership, tambon health promoting hospital

Procedia PDF Downloads 412

Authors: Younes El Khchine, Mohammed Sriti

Abstract:

A parametric study has been conducted to analyse the flow around S809 airfoil of wind turbine in order to better understand the characteristics and effects of laminar separation bubble (LSB) on aerodynamic design for maximizing wind turbine efficiency. Numerical simulations were performed at low Reynolds number by solving the Unsteady Reynolds Averaged Navier-Stokes (URANS) equations based on C-type structural mesh and using γ-Reθt turbulence model. Two-dimensional study was conducted for the chord Reynolds number of 1×105 and angles of attack (AoA) between 0 and 20.15 degrees. The simulation results obtained for the aerodynamic coefficients at various angles of attack (AoA) were compared with XFoil results. A sensitivity study was performed to examine the effects of Reynolds number and free-stream turbulence intensity on the location and length of laminar separation bubble and aerodynamic performances of wind turbine. The results show that increasing the Reynolds number leads to a delay in the laminar separation on the upper surface of the airfoil. The increase in Reynolds number leads to an accelerate transition process and the turbulent reattachment point move closer to the leading edge owing to an earlier reattachment of the turbulent shear layer. This leads to a considerable reduction in the length of the separation bubble as the Reynolds number is increased. The increase of the level of free-stream turbulence intensity leads to a decrease in separation bubble length and an increase the lift coefficient while having negligible effects on the stall angle. When the AoA increased, the bubble on the suction airfoil surface was found to moves upstream to leading edge of the airfoil that causes earlier laminar separation.

Keywords: laminar separation bubble, turbulence intensity, S809 airfoil, transition model, Reynolds number

Procedia PDF Downloads 47

Authors: Assel E. Molzhigitova, Amankeldi K. Sadanov, Elvira T. Ismailova, Kulyash A. Iskandarova, Olga N. Shemshura, Ainur I. Seitbattalova

Abstract:

Fire blight is a very harmful for commercial apple and pear production quarantine bacterial disease. To date, several different methods have been proposed for disease control, including the use of copperbased preparations and antibiotics, which are not always reliable or effective. The use of bacteria as biocontrol agents is one of the most promising and eco-friendly alternative methods. Bacteria with protective activity against the causal agent of fire blight are often present among the epiphytic microorganisms of the phyllosphere of host plants. Therefore, the main objective of our study was screening of local epiphytic bacteria as possible antagonists against Erwinia amylovora, the causal agent of fire blight. Samples of infected organs of apple and pear trees (shoots, leaves, fruits) were collected from the industrial horticulture areas in various agro-ecological zones of Kazakhstan. Epiphytic microorganisms were isolated by standard and modified methods on specific nutrient media. The primary screening of selected microorganisms under laboratory conditions to determine the ability to suppress the growth of Erwinia amylovora was performed by agar-diffusion-test. Among 142 bacteria isolated from the fire blight host plants, 5 isolates, belonging to the genera Bacillus, Lactobacillus, Pseudomonas, Paenibacillus and Pantoea showed higher antagonistic activity against the pathogen. The diameters of inhibition zone have been depended on the species and ranged from 10 mm to 48 mm. The maximum diameter of inhibition zone (48 mm) was exhibited by B. amyloliquefaciens. Less inhibitory effect was showed by Pantoea agglomerans PA1 (19 mm). The study of inhibitory effect of Lactobacillus species against E. amylovora showed that among 7 isolates tested only one (Lactobacillus plantarum 17M) demonstrated inhibitory zone (30 mm). In summary, this study was devoted to detect the beneficial epiphytic bacteria from plants organs of pear and apple trees due to fire blight control in Kazakhstan. Results obtained from the in vitro experiments showed that the most efficient bacterial isolates are Lactobacillus plantarum 17M, Bacillus amyloliquefaciens MB40, and Pantoea agglomerans PA1. These antagonists are suitable for development as biocontrol agents for fire blight control. Their efficacies will be evaluated additionally, in biological tests under in vitro and field conditions during our further study.

Keywords: antagonists, epiphytic bacteria, Erwinia amylovora, fire blight

Procedia PDF Downloads 138

Authors: Piya Roychoudhury, Ruma Pal

Abstract:

Cyanobacteria, commonly known as blue green algae were found to be an effective bioreagent for nanoparticle synthesis. Nowadays silver nanoparticles (AgNPs) are very popular due to their antimicrobial and anti-proliferative activity. To exploit these characters in different biotechnological fields, it is very essential to synthesize more stable, non-toxic nano-silver. For this reason silver-gold alloy (Ag-AuNPs) nanoparticles are of great interest as they are more stable, harder and more effective than single metal nanoparticles. In the present communication we described a simple technique for rapid synthesis of biocompatible AgNP and Ag-AuNP employing cyanobacteria, Leptolyngbya and Lyngbya respectively. For synthesis of AgNP the biomass of Leptolyngbya valderiana (200 mg Fresh weight) was exposed to 9 mM AgNO3 solution (pH 4). For synthesis of Ag-AuNP Lyngbya majuscula (200 mg Fresh weight) was exposed to equimolar solution of hydrogen tetra-auro chlorate and silver nitrate (1mM, pH 4). After 72 hrs of exposure thallus of Leptolyngyba turned brown in color and filaments of Lyngbya turned pink in color that indicated synthesis of nanoparticles. The produced particles were extracted from the cyanobacterial biomass using nano-capping agent, sodium citrate. Firstly, extracted brown and pink suspensions were taken for Energy Dispersive X-ray (EDAX) analysis to confirm the presence of silver in brown suspension and presence of both gold and silver in pink suspension. Extracted nanoparticles showed a distinct single plasmon band (AgNP at 411 nm; Ag-Au NP at 481 nm) in Uv-vis spectroscopy. It was revealed from Transmission electron microscopy (TEM) that all the synthesized particles were spherical in nature with a size range of ~2-25 nm. In X-ray powder diffraction (XRD) analysis four intense peaks appeared at 38.2°, 44.5°, 64.8°and 77.8° which confirmed the crystallographic nature of synthesized particles. Presence of different functional groups viz. N-H, C=C, C–O, C=O on the surface of nanoparticles were recorded by Fourier transform infrared spectroscopy (FTIR). Scanning Electron microscopy (SEM) images showed the surface topography of metal treated filaments of cyanobacteria. The stability of the particles was observed by Zeta potential study. Antibiotic property of synthesized particles was tested by Agar well diffusion method against gram negative bacteria Pseudomonas aeruginosa. Overall, this green-technique requires low energy, less manufacturing cost and produces rapidly eco-friendly metal nanoparticles.

Keywords: cyanobacteria, silver nanoparticles, silver-gold alloy nanoparticles, spectroscopy

Procedia PDF Downloads 292

Authors: P. L. Madhushi Kavindya

Abstract:

Sri Lanka is a developing country where hydrology plays an important role in its economic and social growth, followed by irrigation and power generation. Therefore, reservoirs are a principal element of the culture and social status of Sri Lankans. The emergence of a newly built reservoir goes along with a community relocation process which eventually causes alterations in the cultural landscape around it. From the 18th century, the emergence of reservoirs has caused major impacts on the landscape of Sri Lanka. Foremost aspects can be identified as the increased and decreased value of the cultural landscape around a reservoir. Community relocation in regard to reservoir projects is discussed as a key factor in the research. The study further carries out observations and findings of the relocation process of reservoirs in global and local contexts. Consequently, the study discusses the vast study area of ‘cultural landscape’ in brief and its behavior overall. Besides, specific data about reservoir-related cultural landscapes in a worldwide context, along with facts about the evolution, has been discussed. The significance and diversity of the Sri Lankan reservoir-related cultural landscape are explored in the succeeding study. This study will mainly identify the existing constraints and tendencies regarding the relocation process in an overall status. The base for the research has been laid thereafter by broadening the study on alterations which occur in the cultural landscape in relevance to reservoir-related relocation. Uma Oya multipurpose development project is selected as the exemplary study area considering its visible impacts. This analysis will indicate strategies, theories, and methods that can be applied to apprehend the impact of the relocation process on the cultural landscape of reservoirs. The research was carried out by conducting the Uma Oya multipurpose development project case study and by defining its cultural landscape and process of relocation. A suitable theoretical framework is developed in order to assess the set of vulnerable areas of a cultural landscape which are likely to change due to relocation. A questionnaire survey is done in order to assess socio-economic aspects, and a GIS data analysis is conducted to analyze the impact on physical aspects. Findings show that the impacts of the cultural landscape fall under both positive and negative categories. It also shows that the previous condition before resettlement and post stages have significant changes, where the previous condition had more socio-economic benefits for the community. And it also shows a clear alteration pattern of physical environment changes. These specifically developed theories, areas of assessment, and strategies, along with the outcomes, can be used for any location with geographical similarities worldwide.

Keywords: cultural diffusion theory, cultural landscape, physical aspects, relocation, reservoirs, socio-economic aspects

Procedia PDF Downloads 139

Authors: Antonio A. M. Laudani, Igor O. Golosnoy, Ole T. Thomsen

Abstract:

Rotor blades of large, modern wind turbines are highly susceptible to downward lightning strikes, as well as to triggering upward lightning; consequently, it is necessary to equip them with an effective lightning protection system (LPS) in order to avoid any damage. The performance of existing LPSs is affected by carbon fibre reinforced polymer (CFRP) structures, which lead to lightning-induced damage in the blades, e.g. via electrical sparks. A solution to prevent internal arcing would be to electrically bond the LPS and the composite structures such that to obtain the same electric potential. Nevertheless, elevated temperatures are achieved at the joint interfaces because of high contact resistance, which melts and vaporises some of the epoxy resin matrix around the bonding. The produced high-pressure gasses open up the bonding and can ignite thermal sparks. The objective of this paper is to predict the current density distribution and the temperature field in the adhesive joint cross-section, in order to check whether the resin pyrolysis temperature is achieved and any damage is expected. The finite element method has been employed to solve both the current and heat transfer problems, which are considered weakly coupled. The mathematical model for electric current includes Maxwell-Ampere equation for induced electric field solved together with current conservation, while the thermal field is found from heat diffusion equation. In this way, the current sub-model calculates Joule heat release for a chosen bonding configuration, whereas the thermal analysis allows to determining threshold values of voltage and current density not to be exceeded in order to maintain the temperature across the joint below the pyrolysis temperature, therefore preventing the occurrence of outgassing. In addition, it provides an indication of the minimal number of bonding points. It is worth to mention that the numerical procedures presented in this study can be tailored and applied to any type of joints other than adhesive ones for wind turbine blades. For instance, they can be applied for lightning protection of aerospace bolted joints. Furthermore, they can even be customized to predict the electromagnetic response under lightning strikes of other wind turbine systems, such as nacelle and hub components.

Keywords: carbon fibre reinforced polymer, equipotential bonding, finite element method, FEM, lightning protection system, LPS, wind turbine blades

Procedia PDF Downloads 136

Authors: Shanawaz Patil, Mohamed Haneef, K. S. Narayanaswamy

Abstract:

In the recent years, aluminum metal matrix composites were most widely used, which are finding wide applications in various field such as automobile, aerospace defense etc., due to their outstanding mechanical properties like low density, light weight, exceptional high levels of strength, stiffness, wear resistance, high temperature resistance, low coefficient of thermal expansion and good formability. In the present work, an effort is made to study the effect of heat treatment on mechanical properties of aluminum 7075 alloy reinforced with constant weight percentage of naturally occurring mineral beryl and varying weight percentage of graphene. The hybrid composites are developed with 0.5 wt. %, 1wt.%, 1.5 wt.% and 2 wt.% of graphene and 6 wt.% of beryl  by stir casting liquid metallurgy route. The cast specimens of unreinforced aluminum alloy and hybrid composite samples were prepared for heat treatment process and subjected to solutionizing treatment (T6) at a temperature of 490±5 ^oC for 8 hours in a muffle furnace followed by quenching in boiling water. The microstructure analysis of as cast and heat treated hybrid composite specimens are examined by scanning electron microscope (SEM). The tensile test and hardness test of unreinforced aluminum alloy and hybrid composites are examined. The wear behavior is examined by pin-on disc apparatus. The results of as cast specimens and heat treated specimens were compared. The heat treated Al7075-Beryl-Graphene hybrid composite had better properties and significantly improved the ultimate tensile strength, hardness and reduced wear loss when compared to aluminum alloy and  as cast hybrid composites.

Keywords: beryl, graphene, heat treatment, mechanical properties

Procedia PDF Downloads 121

Authors: Wael M. Rabeh, Cesar Carrasco-Lopez, Juliana C. Ferreira, Pance Naumov

Abstract:

Bioluminescence, the emission of light from a biological process, is found in various living organisms including bacteria, fireflies, beetles, fungus and different marine organisms. Luciferase is an enzyme that catalyzes a two steps oxidation of luciferin in the presence of Mg2+ and ATP to produce oxyluciferin and releases energy in the form of light. The luciferase assay is used in biological research and clinical applications for in vivo imaging, cell proliferation, and protein folding and secretion analysis. The luciferase enzyme consists of two domains, a large N-terminal domain (1-436 residues) that is connected to a small C-terminal domain (440-544) by a flexible loop that functions as a hinge for opening and closing the active site. The two domains are separated by a large cleft housing the active site that closes after binding the substrates, luciferin and ATP. Even though all insect luciferases catalyze the same chemical reaction and share 50% to 90% sequence homology and high structural similarity, they emit light of different colors from green at 560nm to red at 640 nm. Currently, the majority of the structural and biochemical studies have been conducted on green-emitting firefly luciferases. To address the color emission mechanism, we expressed and purified two luciferase enzymes with blue-shifted green and red emission from indigenous Brazilian species Amydetes fanestratus and Phrixothrix, respectively. The two enzymes naturally emit light of different colors and they are an excellent system to study the color-emission mechanism of luciferases, as the current proposed mechanisms are based on mutagenesis studies. Using a vapor-diffusion method and a high-throughput approach, we crystallized and solved the crystal structure of both enzymes, at 1.7 Å and 3.1 Å resolution respectively, using X-ray crystallography. The free enzyme adopted two open conformations in the crystallographic unit cell that are different from the previously characterized firefly luciferase. The blue-shifted green luciferase crystalized as a monomer similar to other luciferases reported in literature, while the red luciferases crystalized as an octamer and was also purified as an octomer in solution. The octomer conformation is the first of its kind for any insect’s luciferase, which might be relate to the red color emission. Structurally designed mutations confirmed the importance of the transition between the open and close conformations in the fine-tuning of the color and the characterization of other interesting mutants is underway.

Keywords: bioluminescence, enzymology, structural biology, x-ray crystallography

Procedia PDF Downloads 304

Authors: Riccardo Patriarca, Giulio Di Gravio, Francesco Costantino, Massimo Tronci

Abstract:

An accurate inventory management policy acquires a crucial role in the several high-availability sectors. In these sectors, due to the high-cost of spares and backorders, an (S-1, S) replenishment policy is necessary for high-availability items. The policy enables the shipment of a substitute efficient item anytime the inventory size decreases by one. This policy can be modelled following the Multi-Echelon Technique for Recoverable Item Control (METRIC). The METRIC is a system-based technique that allows defining the optimum stock level in a multi-echelon network, adopting measures in line with the decision-maker’s perspective. The METRIC defines an availability-cost function with inventory costs and required service levels, using as inputs data about the demand trend, the supplying and maintenance characteristics of the network and the budget/availability constraints. The traditional METRIC relies on the hypothesis that a Poisson distribution well represents the demand distribution in case of items with a low failure rate. However, in this research, we will explore the effects of using a Poisson distribution to model the demand of low failure rate items characterized by an irregular demand trend. This characteristic of a demand is not included in the traditional METRIC formulation leading to the need of revising its traditional formulation. Using the CV (Coefficient of Variation) and ADI (Average inter-Demand Interval) classification, we will define the inherent flaws of Poisson-based METRIC for irregular demand items, defining an innovative ad hoc distribution which can better fit the irregular demands. This distribution will allow defining proper stock levels to reduce stocking and backorder costs due to the high irregularities in the demand trend. A case study in the aviation domain will clarify the benefits of this innovative METRIC approach.

Keywords: METRIC, inventory management, irregular demand, spare parts

Procedia PDF Downloads 319

Authors: Isabel Brás, Artur Figueirinha, Bruno Esteves, Luísa P. Cruz-Lopes

Abstract:

The agriculture lignocellulosic by-products are receiving increased attention, namely in the search for filter materials that retain contaminants from water. These by-products, specifically almond and hazelnut shells are abundant in Portugal once almond and hazelnuts production is a local important activity. Hazelnut and almond shells have as main constituents lignin, cellulose and hemicelluloses, water soluble extractives and tannins. Along the adsorption of heavy metals from contaminated waters, water soluble compounds can leach from shells and have a negative impact in the environment. Usually, the chemical characterization of treated water by itself may not show environmental impact caused by the discharges when parameters obey to legal quality standards for water. Only biological systems can detect the toxic effects of the water constituents. Therefore, the evaluation of toxicity by biological tests is very important when deciding the suitability for safe water discharge or for irrigation applications. The main purpose of the present work was to assess the potential impacts of waters after been treated for heavy metal removal by hazelnut and almond shells adsorption systems, with short term acute toxicity tests. To conduct the study, water at pH 6 with 25 mg.L-1 of lead, was treated with 10 g of shell per litre of wastewater, for 24 hours. This procedure was followed for each bark. Afterwards the water was collected for toxicological assays; namely bacterial resistance, seed germination, Lemna minor L. test and plant grow. The effect in isolated bacteria strains was determined by disc diffusion method and the germination index of seed was evaluated using lettuce, with temperature and humidity germination control for 7 days. For aquatic higher organism, Lemnas were used with 4 days contact time with shell solutions, in controlled light and temperature. For terrestrial higher plants, biomass production was evaluated after 14 days of tomato germination had occurred in soil, with controlled humidity, light and temperature. Toxicity tests of water treated with shells revealed in some extent effects in the tested organisms, with the test assays showing a close behaviour as the control, leading to the conclusion that its further utilization may not be considered to create a serious risk to the environment.

Keywords: lignocellulosic wastes, adsorption, acute toxicity tests, risk assessment

Procedia PDF Downloads 346