Search results for: correlation structures
6309 Anthropometric Indices of Obesity and Coronary Artery Atherosclerosis: An Autopsy Study in South Indian population
Authors: Francis Nanda Prakash Monteiro, Shyna Quadras, Tanush Shetty
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The association between human physique and morbidity and mortality resulting from coronary artery disease has been studied extensively over several decades. Multiple studies have also been done on the correlation between grade of atherosclerosis, coronary artery diseases and anthropometrical measurements. However, the number of autopsy-based studies drastically reduces this number. It has been suggested that while in living subjects, it would be expensive, difficult, and even harmful to subject them to imaging modalities like CT scans and procedures involving contrast media to study mild atherosclerosis, no such harm is encountered in study of autopsy cases. This autopsy-based study was aimed to correlate the anthropometric measurements and indices of obesity, such as waist circumference (WC), hip circumference (HC), body mass index (BMI) and waist hip ratio (WHR) with the degree of atherosclerosis in the right coronary artery (RCA), main branch of the left coronary artery (LCA) and the left anterior descending artery (LADA) in 95 South Indian origin victims of both the genders between the age of 18 years and 75 years. The grading of atherosclerosis was done according to criteria suggested by the American Heart Association. The study also analysed the correlation of the anthropometric measurements and indices of obesity with the number of coronaries affected with atherosclerosis in an individual. All the anthropometric measurements and the derived indices were found to be significantly correlated to each other in both the genders except for the age, which is found to have a significant correlation only with the WHR. In both the genders severe degree of atherosclerosis was commonly observed in LADA, followed by LCA and RCA. Grade of atherosclerosis in RCA is significantly related to the WHR in males. Grade of atherosclerosis in LCA and LADA is significantly related to the WHR in females. Significant relation was observed between grade of atherosclerosis in RCA and WC, and WHR, and between grade of atherosclerosis in LADA and HC in males. Significant relation was observed between grade of atherosclerosis in RCA and WC, and WHR, and between grade of atherosclerosis in LADA and HC in females. Anthropometric measurements/indices of obesity can be an effective means to identify high risk cases of atherosclerosis at an early stage that can be effective in reducing the associated cardiac morbidity and mortality. A person with anthropometric measurements suggestive of mild atherosclerosis can be advised to modify his lifestyle, along with decreasing his exposure to the other risk factors. Those with measurements suggestive of higher degree of atherosclerosis can be subjected to confirmatory procedures to start effective treatment.Keywords: atherosclerosis, coronary artery disease, indices, obesity
Procedia PDF Downloads 676308 Family Cohesion, Interpersonal Difficulties and Mental Health Problems in University Students
Authors: Narmeen Ali, Muhammad Arshad
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Cohesion has an exact association with family functioning and enmeshment (togetherness) on one side and disengagement (separateness) on the other. Family cohesion can apprehend as a concerned association that family members have with each other and an affirmation of association inside the family. Family cohesion, assigned as the level of congruity or sympathetic or emotional attachment that relatives have toward each other, and it was seen to be associated with relational well-being and feeling of comfort in the young generation. The cross-sectional research design was used by the researcher to answer the research questions. A stratified sampling technique was used to collect the data from the participants. The data was collected equally from the males and females of different universities and different departments of Lahore, Pakistan. A self-report questionnaire was developed of given literature and which were found to be associated with family cohesion, interpersonal difficulties and mental health problems of university students. The demographic information included age, gender, university’s name, class, family system, parent’s education, parent’s profession, number of siblings and birth order. Correlation shows the negative relation between balanced cohesion and interpersonal difficulties, while interpersonal difficulties have a highly positive relationship with mental health problems. Mental health problems also have a negative correlation with the balanced family cohesion. Gender, family system, depression and anxiety are the significant predictors of interpersonal difficulties scale in university students. And gender showed a significant difference regarding family cohesion and interpersonal difficulty scale, as women reported more interpersonal difficulties than men.Keywords: family cohesion, interpersonal difficulties, mental health problems, university students
Procedia PDF Downloads 1286307 A Comparative Study on Creep Modeling in Composites
Authors: Roham Rafiee, Behzad Mazhari
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Composite structures, having incredible properties, have gained considerable popularity in the last few decades. Among all types, polymer matrix composites are being used extensively due to their unique characteristics including low weight, convenient fabrication process and low cost. Having polymer as matrix, these type of composites show different creep behavior when compared to metals and even other types of composites since most polymers undergo creep even in room temperature. One of the most challenging topics in creep is to introduce new techniques for predicting long term creep behavior of materials. Depending on the material which is being studied the appropriate method would be different. Methods already proposed for predicting long term creep behavior of polymer matrix composites can be divided into five categories: (1) Analytical Modeling, (2) Empirical Modeling, (3) Superposition Based Modeling (Semi-empirical), (4) Rheological Modeling, (5) Finite Element Modeling. Each of these methods has individual characteristics. Studies have shown that none of the mentioned methods can predict long term creep behavior of all PMC composites in all circumstances (loading, temperature, etc.) but each of them has its own priority in different situations. The reason to this issue can be found in theoretical basis of these methods. In this study after a brief review over the background theory of each method, they are compared in terms of their applicability in predicting long-term behavior of composite structures. Finally, the explained materials are observed through some experimental studies executed by other researchers.Keywords: creep, comparative study, modeling, composite materials
Procedia PDF Downloads 4436306 Nexus Between Agricultural Insurance Scheme and Performance of Agribusiness in Nigeria
Authors: Festus Epetimehin
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Agriculture remains the dominant sector in the rural areas where over 70% of Nigerian reside and it’s still the backbone of our economy. The observed poor performance of farmers in agricultural productivity is due to the nature of risks and uncertainties in agriculture.Agricultural insurance is one of the mechanisms by which farmers can stabilize farm income and investment. The study examined the relationship between agricultural insurance scheme (AIS) and performance of agribusiness in Nigeria. The study adopted exploratory research design which is an ex-ante research approach. One hundred copies of structured questionnaire were administered for the purpose of the study. Correlation analysis and regression analysis were employed for the study. The correlation analysis of the finding revealed that the independent variable; agricultural insurance scheme (AIS) is positively and significantly correlated with the set of dependent variables; where turnover (ABT)=0.582**, profitability (ABP)=0.321**, solvency (ABS)=0.418**and cost of production (ABC)=0.23** respectively. The regression analysis result also revealed the degree of relationship between the independent variable (AIS) and set of dependent variables where one(1%) percent increase in independent variable will lead to 33.9% (ABT), 9.7% (ABP), 17.5%(ABS) and 1.5%(ABC).The study recommended that the Federal Government in collaboration with the participating Agricultural insurers embark on awareness campaign through to the length and breadth of Nigeria on government support and insurance scheme for farmers. Government should also ensure that the loan and insurance scheme should extend beyond the mechanized farmers and include the intensive subsistence farmers in view of the fact that they are the dominants in most of the farm produce markets.Keywords: agribusiness, agricultural insurance, performance, turnover, solvency, agricultural risks
Procedia PDF Downloads 986305 Prediction of PM₂.₅ Concentration in Ulaanbaatar with Deep Learning Models
Authors: Suriya
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Rapid socio-economic development and urbanization have led to an increasingly serious air pollution problem in Ulaanbaatar (UB), the capital of Mongolia. PM₂.₅ pollution has become the most pressing aspect of UB air pollution. Therefore, monitoring and predicting PM₂.₅ concentration in UB is of great significance for the health of the local people and environmental management. As of yet, very few studies have used models to predict PM₂.₅ concentrations in UB. Using data from 0:00 on June 1, 2018, to 23:00 on April 30, 2020, we proposed two deep learning models based on Bayesian-optimized LSTM (Bayes-LSTM) and CNN-LSTM. We utilized hourly observed data, including Himawari8 (H8) aerosol optical depth (AOD), meteorology, and PM₂.₅ concentration, as input for the prediction of PM₂.₅ concentrations. The correlation strengths between meteorology, AOD, and PM₂.₅ were analyzed using the gray correlation analysis method; the comparison of the performance improvement of the model by using the AOD input value was tested, and the performance of these models was evaluated using mean absolute error (MAE) and root mean square error (RMSE). The prediction accuracies of Bayes-LSTM and CNN-LSTM deep learning models were both improved when AOD was included as an input parameter. Improvement of the prediction accuracy of the CNN-LSTM model was particularly enhanced in the non-heating season; in the heating season, the prediction accuracy of the Bayes-LSTM model slightly improved, while the prediction accuracy of the CNN-LSTM model slightly decreased. We propose two novel deep learning models for PM₂.₅ concentration prediction in UB, Bayes-LSTM, and CNN-LSTM deep learning models. Pioneering the use of AOD data from H8 and demonstrating the inclusion of AOD input data improves the performance of our two proposed deep learning models.Keywords: deep learning, AOD, PM2.5, prediction, Ulaanbaatar
Procedia PDF Downloads 486304 Analysis of Basic Science Curriculum as Correlates of Secondary School Students' Achievement in Science Test in Oyo State
Authors: Olubiyi Johnson Ezekiel
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Basic science curriculum is an on-going effort towards developing the potential of manner to produce individuals in a holistic and integrated person, who are intellectually, spiritually, emotionally and physically balanced and harmonious. The main focus of this study is to determine the relationship between students’ achievement in junior school certificate examination (JSCE) and senior school basic science achievement test (SSBSAT) on the basis of all the components of basic science. The study employed the descriptive research of the survey type and utilized junior school certificate examination and senior school basic science achievement test(r = .87) scores as instruments. The data collected were subjected to Pearson product moment correlation, Spearman rank correlation, regression analysis and analysis of variance. The result of the finding revealed that the mean effects of the achievement in all the components of basic science on SSBSAT are significantly different from zero. Based on the results of the findings, it was concluded that the relationship between students’ achievement in JSCE and SSBSAT was weak and to achieve a unit increase in the students’ achievement in the SSBSAT when other subjects are held constant, we have to increase the learning of: -physics by 0.081 units; -chemistry by 0.072 units; -biology by 0.025 units and general knowledge by 0.097 units. It was recommended among others, that general knowledge aspect of basic science should be included in either physics or chemistry aspect of basic science.Keywords: basic science curriculum, students’ achievement, science test, secondary school students
Procedia PDF Downloads 4516303 Effect of the Concrete Cover on the Bond Strength of the FRP Wrapped and Non-Wrapped Reinforced Concrete Beam with Lap Splice under Uni-Direction Cyclic Loading
Authors: Rayed Alyousef, Tim Topper, Adil Al-Mayah
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Many of the reinforced concrete structures subject to cyclic load constructed before the modern bond and fatigue design code. One of the main issue face on exists structure is the bond strength of the longitudinal steel bar and the surrounding concrete. A lap splice is a common connection method to transfer the force between the steel rebar in a reinforced concrete member. Usually, the lap splice is the weak connection on the bond strength. Fatigue flexural loading imposes severe demands on the strength and ductility of the lap splice region in reinforced concrete structures and can lead to a brittle and sudden failure of the member. This paper investigates the effect of different concrete covers on the fatigue bond strength of reinforcing concrete beams containing a lap splice under a fatigue loads. It includes tests of thirty-seven beams divided into three groups. Each group has beams with 30 mm and 50 mm clear side and bottom concrete covers. The variables that were addressed where the concrete cover, the presence or absence of CFRP or GFRP sheet wrapping, the type of loading (monotonic or fatigue) and the fatigue load ranges. The test results showed that an increase in the concrete cover led to an increase in the bond strength under both monotonic and fatigue loading for both the unwrapped and wrapped beams. Also, the FRP sheets increased both the fatigue strength and the ductility for both the 30 mm and the 50 mm concrete covers.Keywords: bond strength, fatigue, Lap splice, FRp wrapping
Procedia PDF Downloads 4896302 Comparison of Corneal Curvature Measurements Conducted with Tomey AO-2000® and the Current Standard Biometer IOL Master®
Authors: Mohd Radzi Hilmi, Khairidzan Mohd Kamal, Che Azemin Mohd Zulfaezal, Ariffin Azrin Esmady
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Purpose: Corneal curvature (CC) is an important anterior segment parameter. This study compared CC measurements conducted with two optical devices in phakic eyes. Methods: Sixty phakic eyes of 30 patients were enrolled in this study. CC was measured three times with the optical biometer and topography-keratometer Tomey AO-2000 (Tomey Corporation, Nagoya, Japan), then with the standard partial optical coherence interferometry (PCI) IOL Master (Carl Zeiss Meditec, Dublin, CA) and data were statistically analysed. Results: The measurements resulted in a mean CC of 43.86 ± 1.57 D with Tomey AO-2000 and 43.84 ± 1.55 D with IOL Master. Distribution of data is normal, and no significance difference in CC values was detected (P = 0.952) between the two devices. Correlation between CC measurements was highly significant (r = 0. 99; P < 0.0001). The mean difference of CC values between devices was 0.017 D and 95% limit of agreement was -0.088 to 0.12. Duration taken for measurements with the standard biometer IOL Master was longer (55.17 ± 2.24 seconds) than with Tomey AO-2000 (39.88 ± 2.38 seconds) in automatic mode. Duration of manual measurement with Tomey AO-2000 in manual mode was the shortest (28.57 ± 2.71 seconds). Conclusion: In phakic eyes, CC measured with Tomey AO-2000 and IOL Master showed similar values, and high correlation was observed between these two devices. This shows that both devices can be used interchangeably. Tomey AO-2000 is better in terms of faster to operate and has its own topography systems.Keywords: corneal topography, corneal curvature, IOL Master, Tomey AO2000
Procedia PDF Downloads 3876301 Influence of Concrete Cracking in the Tensile Strength of Cast-in Headed Anchors
Authors: W. Nataniel, B. Lima, J. Manoel, M. P. Filho, H. Marcos, Oliveira Mauricio, P. Ferreira
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Headed reinforcement bars are increasingly used for anchorage in concrete structures. Applications include connections in composite steel-concrete structures, such as beam-column joints, in several strengthening situations as well as in more traditional uses in cast-in-place and precast structural systems. This paper investigates the reduction in the ultimate tensile capacity of embedded cast-in headed anchors due to concrete cracking. A series of nine laboratory tests are carried out to evaluate the influence of cracking on the concrete breakout strength in tension. The experimental results show that cracking affects both the resistance and load-slip response of the headed bar anchors. The strengths measured in these tests are compared to theoretical resistances calculated following the recommendations presented by fib Bulletin no. 58 (2011), ETAG 001 (2010) and ACI 318 (2014). The influences of parameters such as the effective embedment depth (hef), bar diameter (ds), and the concrete compressive strength (fc) are analysed and discussed. The theoretical recommendations are shown to be over-conservative for both embedment depths and were, in general, inaccurate in comparison to the experimental trends. The ACI 318 (2014) was the design code which presented the best performance regarding to the predictions of the ultimate load, with an average of 1.42 for the ratio between the experimental and estimated strengths, standard deviation of 0.36, and coefficient of variation equal to 0.25.Keywords: cast-in headed anchors, concrete cone failure, uncracked concrete, cracked concrete
Procedia PDF Downloads 2056300 Assessment of Korea's Natural Gas Portfolio Considering Panama Canal Expansion
Authors: Juhan Kim, Jinsoo Kim
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South Korea cannot import natural gas in any form other than LNG because of the division of South and North Korea. Further, the high proportion of natural gas in the national energy mix makes this resource crucial for energy security in Korea. Expansion of Panama Canal will allow for reducing the cost of shipping between the Far East and U.S East. Panama Canal expansion can have significant impacts on South Korea. Due to this situation, we review the natural gas optimal portfolio by considering the uniqueness of the Korean Natural gas market and expansion of Panama Canal. In order to assess Korea’s natural gas optimal portfolio, we developed natural gas portfolio model. The model comprises two steps. First, to obtain the optimal long-term spot contract ratio, the study examines the price level and the correlation between spot and long-term contracts by using the Markowitz, portfolio model. The optimal long-term spot contract ratio follows the efficient frontier of the cost/risk level related to this price level and degree of correlation. Second, by applying the obtained long-term contract purchase ratio as the constraint in the linear programming portfolio model, we determined the natural gas optimal import portfolio that minimizes total intangible and tangible costs. Using this model, we derived the optimal natural gas portfolio considering the expansion of Panama Canal. Based on these results, we assess the portfolio for natural gas import to Korea from the perspective of energy security and present some relevant policy proposals.Keywords: natural gas, Panama Canal, portfolio analysis, South Korea
Procedia PDF Downloads 2916299 Training in Communicational Skills in Students of Medicine: Differences in Bilingualism
Authors: Naiara Ozamiz Etcebarria, Sonia Ruiz De Azua Garcia, Agurtzane Ortiz Jauregi, Virginia Guillen Cañas
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Introduction: The most relevant competencies of a health professional are an adequate communication capacity, which will influence the satisfaction of professionals and patients, therapeutic compliance, conflict prevention, clinical outcomes´ improvement and efficiency of health services. The ability of Active listening , empathy, assertiveness and social skills, are important abilities to develop in all professions in which there is a relationship with other people. In the field of health, it is even more important to have adequate qualities so that the treatment with the patient will be adequate and satisfactory. We conducted a research with students of third year in the Degree of Medicine with the objectives: - to know how the active listening, empathy, assertiveness and social skills of students are. - to know if there are differences according to different demographic variables, such as sex, language, age, number of siblings and interest in the subject. Material and Methods: The students of the Third year in the Degree of Medicine (N = 212) participated voluntarily. Sociodemographic data were collected. Descriptive and comparative analysis of the averages of the students with respect to active listening, empathy, assertiveness and social skills were performed. Once the questionnaires were collected, they were entered into the SPSS 21 database. Four communicational aspects were evaluated: The active listening questionnaire, the TECA empathy questionnaire, the ACDA questionnaire and the EHS questionnaire Social Skills Scale. The active listening questionnaire assesses these factors: Listening without interruption and less contradiction, Listening with 100% attention, Listening beyond words, Listening encouraging the other to go deeper. The TECA questionnaire of cognitive and affective empathy evaluates: Adoption of perspectives, Emotional Comprehension, Emphasizing stress, Empathic joy. The EHS questionnaire Social Skills Scale: Self-expression in social situations, Defending one's own rights as a consumer, Expressing anger or dissatisfaction, Refusing to do and cutting interactions off, Making requests, Initiating positive interactions with the other sex. The ACDA questionnaire Assertiveness Assessment Scale evaluates self-assertiveness and heteroaservitivity. Applicability: To train these skills is so important for clinical practice of medical students and these capabilities that can be measured in a longitudinal way time. Ethical-legal aspects: The data were anonymous. The study was approved by the Ethics Committee. Results: The students of the Third year in the Degree of Medicine (34.4% Basque speakers and 65.6% Spanish speakers) with average age 20.93, (27.8% men and 72.2% women). There are no differences in social skills between men and women. The Basque speaker students of are more heteroactive (ACDA) than Spanish students. Active listening has a high correlation with social skills, especially with self-expression in social situations. Listening without interruption has a high correlation with self-expression in social situations and initiating positive interactions with the opposite sex. Adoption of perspectives presents a high correlation with auto- assertiveness. Emotional understanding presents a high correlation with positive interactions with the opposite sex. Empathic joy correlates with self-assertiveness, self-expression in social situations, and initiating positive interactions with the opposite sex.Keywords: active listening, assertiveness, communicational skills, empathy, students of medicine
Procedia PDF Downloads 3046298 Multi-Objectives Genetic Algorithm for Optimizing Machining Process Parameters
Authors: Dylan Santos De Pinho, Nabil Ouerhani
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Energy consumption of machine-tools is becoming critical for machine-tool builders and end-users because of economic, ecological and legislation-related reasons. Many machine-tool builders are seeking for solutions that allow the reduction of energy consumption of machine-tools while preserving the same productivity rate and the same quality of machined parts. In this paper, we present the first results of a project conducted jointly by academic and industrial partners to reduce the energy consumption of a Swiss-Type lathe. We employ genetic algorithms to find optimal machining parameters – the set of parameters that lead to the best trade-off between energy consumption, part quality and tool lifetime. Three main machining process parameters are considered in our optimization technique, namely depth of cut, spindle rotation speed and material feed rate. These machining process parameters have been identified as the most influential ones in the configuration of the Swiss-type machining process. A state-of-the-art multi-objective genetic algorithm has been used. The algorithm combines three fitness functions, which are objective functions that permit to evaluate a set of parameters against the three objectives: energy consumption, quality of the machined parts, and tool lifetime. In this paper, we focus on the investigation of the fitness function related to energy consumption. Four different energy consumption related fitness functions have been investigated and compared. The first fitness function refers to the Kienzle cutting force model. The second fitness function uses the Material Removal Rate (RMM) as an indicator of energy consumption. The two other fitness functions are non-deterministic, learning-based functions. One fitness function uses a simple Neural Network to learn the relation between the process parameters and the energy consumption from experimental data. Another fitness function uses Lasso regression to determine the same relation. The goal is, then, to find out which fitness functions predict best the energy consumption of a Swiss-Type machining process for the given set of machining process parameters. Once determined, these functions may be used for optimization purposes – determine the optimal machining process parameters leading to minimum energy consumption. The performance of the four fitness functions has been evaluated. The Tornos DT13 Swiss-Type Lathe has been used to carry out the experiments. A mechanical part including various Swiss-Type machining operations has been selected for the experiments. The evaluation process starts with generating a set of CNC (Computer Numerical Control) programs for machining the part at hand. Each CNC program considers a different set of machining process parameters. During the machining process, the power consumption of the spindle is measured. All collected data are assigned to the appropriate CNC program and thus to the set of machining process parameters. The evaluation approach consists in calculating the correlation between the normalized measured power consumption and the normalized power consumption prediction for each of the four fitness functions. The evaluation shows that the Lasso and Neural Network fitness functions have the highest correlation coefficient with 97%. The fitness function “Material Removal Rate” (MRR) has a correlation coefficient of 90%, whereas the Kienzle-based fitness function has a correlation coefficient of 80%.Keywords: adaptive machining, genetic algorithms, smart manufacturing, parameters optimization
Procedia PDF Downloads 1486297 Statistical Analysis of Parameters Effects on Maximum Strain and Torsion Angle of FRP Honeycomb Sandwich Panels Subjected to Torsion
Authors: Mehdi Modabberifar, Milad Roodi, Ehsan Souri
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In recent years, honeycomb fiber reinforced plastic (FRP) sandwich panels have been increasingly used in various industries. Low weight, low price, and high mechanical strength are the benefits of these structures. However, their mechanical properties and behavior have not been fully explored. The objective of this study is to conduct a combined numerical-statistical investigation of honeycomb FRP sandwich beams subject to torsion load. In this paper, the effect of geometric parameters of the sandwich panel on the maximum shear strain in both face and core and angle of torsion in a honeycomb FRP sandwich structures in torsion is investigated. The effect of Parameters including core thickness, face skin thickness, cell shape, cell size, and cell thickness on mechanical behavior of the structure were numerically investigated. Main effects of factors were considered in this paper and regression equations were derived. Taguchi method was employed as experimental design and an optimum parameter combination for the maximum structure stiffness has been obtained. The results showed that cell size and face skin thickness have the most significant impacts on torsion angle, maximum shear strain in face and core.Keywords: finite element, honeycomb FRP sandwich panel, torsion, civil engineering
Procedia PDF Downloads 4186296 Form of Distribution of Traffic Accident and Environment Factors of Road Affecting of Traffic Accident in Dusit District, Only Area Responsible of Samsen Police Station
Authors: Musthaya Patchanee
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This research aimed to study form of traffic distribution and environmental factors of road that affect traffic accidents in Dusit District, only areas responsible of Samsen Police Station. Data used in this analysis is the secondary data of traffic accident case from year 2011. Observed area units are 15 traffic lines that are under responsible of Samsen Police Station. Technique and method used are the Cartographic Method, the Correlation Analysis, and the Multiple Regression Analysis. The results of form of traffic accidents show that, the Samsen Road area had most traffic accidents (24.29%), second was Rachvithi Road (18.10%), third was Sukhothai Road (15.71%), fourth was Rachasrima Road (12.38%), and fifth was Amnuaysongkram Road (7.62%). The result from Dusit District, only areas responsible of Samsen police station, has suggested that the scale of accidents have high positive correlation with statistic significant at level 0.05 and the frequency of travel (r=0.857). Traffic intersection point (r=0.763)and traffic control equipments (r=0.713) are relevant factors respectively. By using the Multiple Regression Analysis, travel frequency is the only one that has considerable influences on traffic accidents in Dusit district only Samsen Police Station area. Also, a factor in frequency of travel can explain the change in traffic accidents scale to 73.40 (R2 = 0.734). By using the Multiple regression summation from analysis was Y ̂=-7.977+0.044X6.Keywords: form of traffic distribution, environmental factors of road, traffic accidents, Dusit district
Procedia PDF Downloads 3916295 Correlation between Copper Uptake and Decrease of Copper (Hypocupremia) in Burn Patients-Infected Pseudomonas aeruginosa
Authors: Khaled M. Khleifat
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Pseudomonas aeruginosa was isolated from infected burn patients and characterized by standard biochemical tests. The in vitro copper uptake was compared between this isolated pathogenic strain and two non-pathogenic control strains of Gram-positive bacteria Bacillusthuringiensis strain Israelisas well as Gram-negative bacteria Enterobacter aerogenes. Maximum copper uptake of 470 ppm/g biomass was obtained by P. aeruginosa strain, while the control strains B. thuringiensis and Enterobacter aerogenes had copper uptake of 350 and 383 ppm/g biomass, respectively. However, the lowest copper uptake (60 ppm/g biomass) was observed with another control the saprophytic strain Pseudomonas (Shewanella) putrefaciens. A further investigation regarding the effect of copper toxicity on bacterial growth, gave an MIC score of 600 ppm for P. aeruginosa strain compared to 460 and 300 ppm for the two Gram positive and Gram negative control strains, respectively. In tandem with these in vitro findings, blood analysis on burn patients infected with P. aeruginosa has indicated a selective decrease of copper (hypocupremia) and ceruloplasmin plasma levels. The iron metabolism was also affected by this copper deprivation leading to a similar decrease in plasma levels of PCV, iron, total iron-binding capacity, and transferrin. All these hematological changes were significantly different (P < 0.05) from the matched group of non-infected burn patients. The observed hypocupremia in infected burn patients was attributed to demanding scavenger ability by P. aeruginosa strain for the copper of plasma.Keywords: Pseudomonas aeruginosa, hypocupremia, correlation, PCV
Procedia PDF Downloads 3136294 Music Reading Expertise Facilitates Implicit Statistical Learning of Sentence Structures in a Novel Language: Evidence from Eye Movement Behavior
Authors: Sara T. K. Li, Belinda H. J. Chung, Jeffery C. N. Yip, Janet H. Hsiao
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Music notation and text reading both involve statistical learning of music or linguistic structures. However, it remains unclear how music reading expertise influences text reading behavior. The present study examined this issue through an eye-tracking study. Chinese-English bilingual musicians and non-musicians read English sentences, Chinese sentences, musical phrases, and sentences in Tibetan, a language novel to the participants, with their eye movement recorded. Each set of stimuli consisted of two conditions in terms of structural regularity: syntactically correct and syntactically incorrect musical phrases/sentences. They then completed a sentence comprehension (for syntactically correct sentences) or a musical segment/word recognition task afterwards to test their comprehension/recognition abilities. The results showed that in reading musical phrases, as compared with non-musicians, musicians had a higher accuracy in the recognition task, and had shorter reading time, fewer fixations, and shorter fixation duration when reading syntactically correct (i.e., in diatonic key) than incorrect (i.e., in non-diatonic key/atonal) musical phrases. This result reflects their expertise in music reading. Interestingly, in reading Tibetan sentences, which was novel to both participant groups, while non-musicians did not show any behavior differences between reading syntactically correct or incorrect Tibetan sentences, musicians showed a shorter reading time and had marginally fewer fixations when reading syntactically correct sentences than syntactically incorrect ones. However, none of the musicians reported discovering any structural regularities in the Tibetan stimuli after the experiment when being asked explicitly, suggesting that they may have implicitly acquired the structural regularities in Tibetan sentences. This group difference was not observed when they read English or Chinese sentences. This result suggests that music reading expertise facilities reading texts in a novel language (i.e., Tibetan), but not in languages that the readers are already familiar with (i.e., English and Chinese). This phenomenon may be due to the similarities between reading music notations and reading texts in a novel language, as in both cases the stimuli follow particular statistical structures but do not involve semantic or lexical processing. Thus, musicians may transfer their statistical learning skills stemmed from music notation reading experience to implicitly discover structures of sentences in a novel language. This speculation is consistent with a recent finding showing that music reading expertise modulates the processing of English nonwords (i.e., words that do not follow morphological or orthographic rules) but not pseudo- or real words. These results suggest that the modulation of music reading expertise on language processing depends on the similarities in the cognitive processes involved. It also has important implications for the benefits of music education on language and cognitive development.Keywords: eye movement behavior, eye-tracking, music reading expertise, sentence reading, structural regularity, visual processing
Procedia PDF Downloads 3836293 Effects of Low Sleep Efficiency and Sleep Deprivation on Driver Physical Fatigue
Authors: Chen-Yu Tsai, Wen-Te Liu, Chen-Chen Lo, Kang Lo, Yin-Tzu Lin
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Background: Driving drowsiness related to insufficient or disordered sleep accounts for a major percentage of vehicular accidents. Sleep deprivation is the primary reason related to low sleep efficiency. Nevertheless, the mechanism of sleep deprivation induces driving fatigue to remain unclear. Objective: The objective of this study is to associate the relationship between insufficient sleep efficiency and driving fatigue. Methodologies: The physical condition while driving was obtained from the questionnaires to classify the state of driving fatigue. Sleep efficiency was quantified as the polysomnography (PSG), and the sleep stages were sentenced by the reregistered Technologist during examination in a hospital in New Taipei City (Taiwan). The independent T-test was used to investigate the correlation between sleep efficiency, sleep stages ratio, and driving drowsiness. Results: There were 880 subjects recruited in this study, who had been done polysomnography for evaluating severity for obstructive sleep apnea syndrome (OSAS) as well as completed the driver condition questionnaire. Four-hundred-eighty-four subjects (55%) were classified as fatigue group, and 396 subjects (45%) were served as the control group. The ratio of stage three sleep (N3) (0.032 ± 0.056) in fatigue group were significantly lower than the control group (p < 0.01). The significantly higher value of snoring index (242.14 ± 205.51 /hours) was observed in the fatigue group (p < 0.01). Conclusion: We observe the considerable correlation between deep sleep reduce and driving drowsiness. To avoid drowsy driving, the sleep deprivation, and the snoring events during the sleeping time should be monitored and alleviated.Keywords: driving drowsiness, sleep deprivation, stage three sleep, snoring index
Procedia PDF Downloads 1466292 Field Studies of 2017 in the Water Catch Basin in the River Vere to Safeguard the Population of Tbilisi against the Erosive-Mudflow Processes and Its Evaluation
Authors: Natia Gavardashvili
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From April through June of 2017, the field-scientific studies to ensure the safety of the population of Tbilisi were accomplished in the water catch basin of the river Vere, in the water catch basin of the river Jakhana dry gully. 5 sensitive sites were identified, and areas, 20x20 m each, were marked around them, with their locations fixed with GPS coordinates. The gained areas were plotted on a digital map, and the state of the surface was explored by considering the evaluation of erosive processes. Aiming at evaluating the soils and grounds of the sensitive areas, the ground samples were taken, and average diameter was identified, with its value changing to D0 = 4,67-15,48 mm, and integral curves of the grain size were drafted. By using the obtained data, the transporting capability of mudflow can be identified at the next stage to use to calculate mudflow peak discharges of different provisions in developing the new designs of mudflow-protection structures with the goal of ensuring the safety of Tbilisi population. The studies were accomplished under the financing of Young Scientists’ Grant of Shota Rustaveli National Science Foundation 'The study of erosive-mudflow processes in the water catch basin in the river Vere to ensure the safety of the population of Tbilisi and their consideration in developing new environmental protection plans' (YS15_2.1.5_8)Keywords: water catch basin, mudflow-protection structures, erosive-mudflow processes, safety
Procedia PDF Downloads 3056291 Quasiperiodic Magnetic Chains as Spin Filters
Authors: Arunava Chakrabarti
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A one-dimensional chain of magnetic atoms, representative of a quantum gas in an artificial quasi-periodic potential and modeled by the well-known Aubry-Andre function and its variants are studied in respect of its capability of working as a spin filter for arbitrary spins. The basic formulation is explained in terms of a perfectly periodic chain first, where it is shown that a definite correlation between the spin S of the incoming particles and the magnetic moment h of the substrate atoms can open up a gap in the energy spectrum. This is crucial for a spin filtering action. The simple one-dimensional chain is shown to be equivalent to a 2S+1 strand ladder network. This equivalence is exploited to work out the condition for the opening of gaps. The formulation is then applied for a one-dimensional chain with quasi-periodic variation in the site potentials, the magnetic moments and their orientations following an Aubry-Andre modulation and its variants. In addition, we show that a certain correlation between the system parameters can generate absolutely continuous bands in such systems populated by Bloch like extended wave functions only, signaling the possibility of a metal-insulator transition. This is a case of correlated disorder (a deterministic one), and the results provide a non-trivial variation to the famous Anderson localization problem. We have worked within a tight binding formalism and have presented explicit results for the spin half, spin one, three halves and spin five half particles incident on the magnetic chain to explain our scheme and the central results.Keywords: Aubry-Andre model, correlated disorder, localization, spin filter
Procedia PDF Downloads 3566290 Experimental Investigation of the Out-of-Plane Dynamic Behavior of Adhesively Bonded Composite Joints at High Strain Rates
Authors: Sonia Sassi, Mostapha Tarfaoui, Hamza Ben Yahia
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In this investigation, an experimental technique in which the dynamic response, damage kinetic and heat dissipation are measured simultaneously during high strain rates on adhesively bonded joints materials. The material used in this study is widely used in the design of structures for military applications. It was composed of a 45° Bi-axial fiber-glass mat of 0.286 mm thickness in a Polyester resin matrix. In adhesive bonding, a NORPOL Polyvinylester of 1 mm thickness was used to assemble the composite substrate. The experimental setup consists of a compression Split Hopkinson Pressure Bar (SHPB), a high-speed infrared camera and a high-speed Fastcam rapid camera. For the dynamic compression tests, 13 mm x 13 mm x 9 mm samples for out-of-plane tests were considered from 372 to 1030 s-1. Specimen surface is controlled and monitored in situ and in real time using the high-speed camera which acquires the damage progressive in specimens and with the infrared camera which provides thermal images in time sequence. Preliminary compressive stress-strain vs. strain rates data obtained show that the dynamic material strength increases with increasing strain rates. Damage investigations have revealed that the failure mainly occurred in the adhesive/adherent interface because of the brittle nature of the polymeric adhesive. Results have shown the dependency of the dynamic parameters on strain rates. Significant temperature rise was observed in dynamic compression tests. Experimental results show that the temperature change depending on the strain rate and the damage mode and their maximum exceed 100 °C. The dependence of these results on strain rate indicates that there exists a strong correlation between damage rate sensitivity and heat dissipation, which might be useful when developing damage models under dynamic loading tacking into account the effect of the energy balance of adhesively bonded joints.Keywords: adhesive bonded joints, Hopkinson bars, out-of-plane tests, dynamic compression properties, damage mechanisms, heat dissipation
Procedia PDF Downloads 2126289 Financial Liberalization and Allocation of Bank Credit in Malaysia
Authors: Chow Fah Yee, Eu Chye Tan
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The main purpose of developing a modern and sophisticated financial system is to mobilize and allocate the country’s resources for productive uses and in the process contribute to economic growth. Financial liberalization introduced in Malaysia in 1978 was said to be a step towards this goal. According to Mc-Kinnon and Shaw, the deregulation of a country’s financial system will create a more efficient and competitive market driven financial sector; with savings being channelled to the most productive users. This paper aims to assess whether financial liberalization resulted in bank credit being allocated to the more productive users, for the case of Malaysia by: firstly, using Chi-square test to if there exists a relationship between financial liberalization and bank lending in Malaysia. Secondly, to analyze on a comparative basis, the share of loans secured by 9 major economic sectors, using data on bank loans from 1975 to 2003. Lastly, present value analysis and rank correlation was used to determine if the recipients of bigger loans are the more efficient users. Chi-square test confirmed the generally observed trend of an increase in bank credit with the adoption of financial liberalization. While the comparative analysis of loans showed that the bulk of credit were allocated to service sectors, consumer loans and property related sectors, at the expense of industry. Results for rank correlation analysis showed that there is no relationship between the more productive users and amount of loans obtained. This implies that the recipients (sectors) that received more loans were not the more efficient sectors.Keywords: allocation of resources, bank credit, financial liberalization, economics
Procedia PDF Downloads 4476288 Preparation and Antioxidant Activity of Heterocyclic Indole Derivatives
Authors: Tunca Gul Altuntas, Aziz Baydar, Cemre Acar, Sezen Yılmaz, Tulay Coban
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Free radicals, which are generated in many bioorganic redox processes, play a role in the pathogenesis of several diseases including cancer, arthritis, hemorrhagic shock, inflammatory, cardiovascular, neurodegenerative diseases and age-related degenerative brain diseases. Exposures of normal cell to free radical damages several structures, oxidizes nucleic acids, proteins, lipids, or DNA. Compounds interfere with the action of reactive oxygen species might be useful in prevention and treatment of these pathologies. A series of indole compounds containing piperazine ring were synthesized. Coupling of indole-2-carboxylic acid with monosubstituted piperazines was accomplished with 1,1’-carbonyldiimidazole (CDI) in a good yield. The structures of prepared compounds were verified in good agreement with their 1H NMR (nuclear magnetic resonance), MS (mass spectrophotometry), and IR (infrared spectrophotometry) characteristics. In this work, all synthetized indole derivatives were screened in vitro for their antioxidative potential against vitamin E (α-tocopherol) using different antioxidant assays such as superoxide anion formation, lipid peroxidation levels in rat liver, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) stable radical scavenging activity. The synthesized compounds showed various levels of inhibition compared to vitamin E. This may give promising results for the development of new antioxidant agents.Keywords: antioxidant, indoles, piperazines, reactive oxygen species
Procedia PDF Downloads 2316287 Molecular Interactions Driving RNA Binding to hnRNPA1 Implicated in Neurodegeneration
Authors: Sakina Fatima, Joseph-Patrick W. E. Clarke, Patricia A. Thibault, Subha Kalyaanamoorthy, Michael Levin, Aravindhan Ganesan
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Heteronuclear ribonucleoprotein (hnRNPA1 or A1) is associated with the pathology of different diseases, including neurological disorders and cancers. In particular, the aggregation and dysfunction of A1 have been identified as a critical driver for neurodegeneration (NDG) in Multiple Sclerosis (MS). Structurally, A1 includes a low-complexity domain (LCD) and two RNA-recognition motifs (RRMs), and their interdomain coordination may play a crucial role in A1 aggregation. Previous studies propose that RNA-inhibitors or nucleoside analogs that bind to RRMs can potentially prevent A1 self-association. Therefore, molecular-level understanding of the structures, dynamics, and nucleotide interactions with A1 RRMs can be useful for developing therapeutics for NDG in MS. In this work, a combination of computational modelling and biochemical experiments were employed to analyze a set of RNA-A1 RRM complexes. Initially, the atomistic models of RNA-RRM complexes were constructed by modifying known crystal structures (e.g., PDBs: 4YOE and 5MPG), and through molecular docking calculations. The complexes were optimized using molecular dynamics simulations (200-400 ns), and their binding free energies were computed. The binding affinities of the selected complexes were validated using a thermal shift assay. Further, the most important molecular interactions that contributed to the overall stability of the RNA-A1 RRM complexes were deduced. The results highlight that adenine and guanine are the most suitable nucleotides for high-affinity binding with A1. These insights will be useful in the rational design of nucleotide-analogs for targeting A1 RRMs.Keywords: hnRNPA1, molecular docking, molecular dynamics, RNA-binding proteins
Procedia PDF Downloads 1216286 Seismic Integrity Determination of Dams in Urban Areas
Authors: J. M. Mayoral, M. Anaya
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The urban and economic development of cities demands the construction of water use and flood control infrastructure. Likewise, it is necessary to determine the safety level of the structures built with the current standards and if it is necessary to define the reinforcement actions. The foregoing is even more important in structures of great importance, such as dams, since they imply a greater risk for the population in case of failure or undesirable operating conditions (e.g., seepage, cracks, subsidence). This article presents a methodology for determining the seismic integrity of dams in urban areas. From direct measurements of the dynamic properties using geophysical exploration and ambient seismic noise measurements, the seismic integrity of the concrete-faced rockfill dam selected as a case of study is evaluated. To validate the results, two accelerometer stations were installed (e.g., free field and crest of the dam). Once the dynamic properties were determined, three-dimensional finite difference models were developed to evaluate the dam seismic performance for different intensities of movement, considering the site response and soil-structure interaction effects. The seismic environment was determined from the uniform hazard spectra for several return periods. Based on the results obtained, the safety level of the dam against different seismic actions was determined, and the effectiveness of ambient seismic noise measurements in dynamic characterization and subsequent evaluation of the seismic integrity of urban dams was evaluated.Keywords: risk, seismic, soil-structure interaction, urban dams
Procedia PDF Downloads 1196285 Determining the Relationship Between Maternal Stress and Depression and Child Obesity: The Mediating Role of Maternal Self-efficacy
Authors: Alireza Monzavi Chaleshtori, Mahnaz Aliakbari Dehkordi, Maryam Aliakbari, Solmaz Seyed Mostafaii
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Objective: Considering the growing obesity among children and the role of mother's psychological factors as well as the need to prevent childhood obesity, this study aimed to investigate the mediating role of mother's self-efficacy in the relationship between mother's stress and depression and child obesity. Method: For this purpose, in a descriptive-correlation study, 222 mothers and children aged 1 to 5 years in Tehran, who had the opportunity to answer an online questionnaire, were selected by random sampling and to the depression scales of the Kroenke and Spitzer Patient Health Questionnaire, Cohen's stress and Self-efficacy of Berkeley mothers answered. Pearson correlation test and path analysis were used for data analysis. Findings: The findings showed that maternal depression had an indirect and significant effect on child obesity, and the effect of stress and depression on child obesity was indirect and non-significant. Therefore, the model has a good fit with the research data, and stress and depression indirectly predicted child obesity with the mediating role of self-efficacy. Conclusion: The hypothesized model tested based on mother's stress and depression with the mediating role of mother's self-efficacy was a good model in explaining the prediction of child obesity. Based on the findings of this research, a practical framework can be provided to explain the psychological factors of the mother in relation to child obesity and its treatment.Keywords: stress, self-efficacy, child obesity, depression
Procedia PDF Downloads 756284 Complex Network Analysis of Seismicity and Applications to Short-Term Earthquake Forecasting
Authors: Kahlil Fredrick Cui, Marissa Pastor
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Earthquakes are complex phenomena, exhibiting complex correlations in space, time, and magnitude. Recently, the concept of complex networks has been used to shed light on the statistical and dynamical characteristics of regional seismicity. In this work, we study the relationships and interactions of seismic regions in Chile, Japan, and the Philippines through weighted and directed complex network analysis. Geographical areas are digitized into cells of fixed dimensions which in turn become the nodes of the network when an earthquake has occurred therein. Nodes are linked if a correlation exists between them as determined and measured by a correlation metric. The networks are found to be scale-free, exhibiting power-law behavior in the distributions of their different centrality measures: the in- and out-degree and the in- and out-strength. The evidence is also found of preferential interaction between seismically active regions through their degree-degree correlations suggesting that seismicity is dictated by the activity of a few active regions. The importance of a seismic region to the overall seismicity is measured using a generalized centrality metric taken to be an indicator of its activity or passivity. The spatial distribution of earthquake activity indicates the areas where strong earthquakes have occurred in the past while the passivity distribution points toward the likely locations an earthquake would occur whenever another one happens elsewhere. Finally, we propose a method that would project the location of the next possible earthquake using the generalized centralities coupled with correlations calculated between the latest earthquakes and a geographical point in the future.Keywords: complex networks, correlations, earthquake, hazard assessment
Procedia PDF Downloads 2146283 Indoor Air Pollution of the Flexographic Printing Environment
Authors: Jelena S. Kiurski, Vesna S. Kecić, Snežana M. Aksentijević
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The identification and evaluation of organic and inorganic pollutants were performed in a flexographic facility in Novi Sad, Serbia. Air samples were collected and analyzed in situ, during 4-hours working time at five sampling points by the mobile gas chromatograph and ozonometer at the printing of collagen casing. Experimental results showed that the concentrations of isopropyl alcohol, acetone, total volatile organic compounds and ozone varied during the sampling times. The highest average concentrations of 94.80 ppm and 102.57 ppm were achieved at 200 minutes from starting the production for isopropyl alcohol and total volatile organic compounds, respectively. The mutual dependences between target hazardous and microclimate parameters were confirmed using a multiple linear regression model with software package STATISTICA 10. Obtained multiple coefficients of determination in the case of ozone and acetone (0.507 and 0.589) with microclimate parameters indicated a moderate correlation between the observed variables. However, a strong positive correlation was obtained for isopropyl alcohol and total volatile organic compounds (0.760 and 0.852) with microclimate parameters. Higher values of parameter F than Fcritical for all examined dependences indicated the existence of statistically significant difference between the concentration levels of target pollutants and microclimates parameters. Given that, the microclimate parameters significantly affect the emission of investigated gases and the application of eco-friendly materials in production process present a necessity.Keywords: flexographic printing, indoor air, multiple regression analysis, pollution emission
Procedia PDF Downloads 1976282 Simulation Research of the Aerodynamic Drag of 3D Structures for Individual Transport Vehicle
Authors: Pawel Magryta, Mateusz Paszko
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In today's world, a big problem of individual mobility, especially in large urban areas, occurs. Commonly used grand way of transport such as buses, trains or cars do not fulfill their tasks, i.e. they are not able to meet the increasing mobility needs of the growing urban population. Additional to that, the limitations of civil infrastructure construction in the cities exist. Nowadays the most common idea is to transfer the part of urban transport on the level of air transport. However to do this, there is a need to develop an individual flying transport vehicle. The biggest problem occurring in this concept is the type of the propulsion system from which the vehicle will obtain a lifting force. Standard propeller drives appear to be too noisy. One of the ideas is to provide the required take-off and flight power by the machine using the innovative ejector system. This kind of the system will be designed through a suitable choice of the three-dimensional geometric structure with special shape of nozzle in order to generate overpressure. The authors idea is to make a device that would allow to cumulate the overpressure using the a five-sided geometrical structure that will be limited on the one side by the blowing flow of air jet. In order to test this hypothesis a computer simulation study of aerodynamic drag of such 3D structures have been made. Based on the results of these studies, the tests on real model were also performed. The final stage of work was a comparative analysis of the results of simulation and real tests. The CFD simulation studies of air flow was conducted using the Star CD - Star Pro 3.2 software. The design of virtual model was made using the Catia v5 software. Apart from the objective to obtain advanced aviation propulsion system, all of the tests and modifications of 3D structures were also aimed at achieving high efficiency of this device while maintaining the ability to generate high value of overpressures. This was possible only in case of a large mass flow rate of air. All these aspects have been possible to verify using CFD methods for observing the flow of the working medium in the tested model. During the simulation tests, the distribution and size of pressure and velocity vectors were analyzed. Simulations were made with different boundary conditions (supply air pressure), but with a fixed external conditions (ambient temp., ambient pressure, etc.). The maximum value of obtained overpressure is 2 kPa. This value is too low to exploit the power of this device for the individual transport vehicle. Both the simulation model and real object shows a linear dependence of the overpressure values obtained from the different geometrical parameters of three-dimensional structures. Application of computational software greatly simplifies and streamlines the design and simulation capabilities. This work has been financed by the Polish Ministry of Science and Higher Education.Keywords: aviation propulsion, CFD, 3d structure, aerodynamic drag
Procedia PDF Downloads 3116281 Spatial Object-Oriented Template Matching Algorithm Using Normalized Cross-Correlation Criterion for Tracking Aerial Image Scene
Authors: Jigg Pelayo, Ricardo Villar
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Leaning on the development of aerial laser scanning in the Philippine geospatial industry, researches about remote sensing and machine vision technology became a trend. Object detection via template matching is one of its application which characterized to be fast and in real time. The paper purposely attempts to provide application for robust pattern matching algorithm based on the normalized cross correlation (NCC) criterion function subjected in Object-based image analysis (OBIA) utilizing high-resolution aerial imagery and low density LiDAR data. The height information from laser scanning provides effective partitioning order, thus improving the hierarchal class feature pattern which allows to skip unnecessary calculation. Since detection is executed in the object-oriented platform, mathematical morphology and multi-level filter algorithms were established to effectively avoid the influence of noise, small distortion and fluctuating image saturation that affect the rate of recognition of features. Furthermore, the scheme is evaluated to recognized the performance in different situations and inspect the computational complexities of the algorithms. Its effectiveness is demonstrated in areas of Misamis Oriental province, achieving an overall accuracy of 91% above. Also, the garnered results portray the potential and efficiency of the implemented algorithm under different lighting conditions.Keywords: algorithm, LiDAR, object recognition, OBIA
Procedia PDF Downloads 2466280 Detection of Defects in CFRP by Ultrasonic IR Thermographic Method
Authors: W. Swiderski
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In the paper introduced the diagnostic technique making possible the research of internal structures in composite materials reinforced fibres using in different applications. The main reason of damages in structures of these materials is the changing distribution of load in constructions in the lifetime. Appearing defect is largely complicated because of the appearance of disturbing of continuity of reinforced fibres, binder cracks and loss of fibres adhesiveness from binders. Defect in composite materials is usually more complicated than in metals. At present, infrared thermography is the most effective method in non-destructive testing composite. One of IR thermography methods used in non-destructive evaluation is vibrothermography. The vibrothermography is not a new non-destructive method, but the new solution in this test is use ultrasonic waves to thermal stimulation of materials. In this paper, both modelling and experimental results which illustrate the advantages and limitations of ultrasonic IR thermography in inspecting composite materials will be presented. The ThermoSon computer program for computing 3D dynamic temperature distribuions in anisotropic layered solids with subsurface defects subject to ulrasonic stimulation was used to optimise heating parameters in the detection of subsurface defects in composite materials. The program allows for the analysis of transient heat conduction and ultrasonic wave propagation phenomena in solids. The experiments at MIAT were fulfilled by means of FLIR SC 7600 IR camera. Ultrasonic stimulation was performed with the frequency from 15 kHz to 30 kHz with maximum power up to 2 kW.Keywords: composite material, ultrasonic, infrared thermography, non-destructive testing
Procedia PDF Downloads 296