Search results for: fish population dynamics
6180 A CFD Analysis of Hydraulic Characteristics of the Rod Bundles in the BREST-OD-300 Wire-Spaced Fuel Assemblies
Authors: Dmitry V. Fomichev, Vladimir V. Solonin
Abstract:
This paper presents the findings from a numerical simulation of the flow in 37-rod fuel assembly models spaced by a double-wire trapezoidal wrapping as applied to the BREST-OD-300 experimental nuclear reactor. Data on a high static pressure distribution within the models, and equations for determining the fuel bundle flow friction factors have been obtained. Recommendations are provided on using the closing turbulence models available in the ANSYS Fluent. A comparative analysis has been performed against the existing empirical equations for determining the flow friction factors. The calculated and experimental data fit has been shown. An analysis into the experimental data and results of the numerical simulation of the BREST-OD-300 fuel rod assembly hydrodynamic performance are presented.Keywords: BREST-OD-300, ware-spaces, fuel assembly, computation fluid dynamics
Procedia PDF Downloads 3826179 Bone Marrow ARA, EPA, and DHA Fatty Acids are Correlated with Femur Minerals Content and Enzyme of Bone Formation in Growing Rabbits
Authors: Al-Nouri Doha Mostfa, Al-Khalifa Abdulrahman Salih
Abstract:
The effects of long-term supplementation with different dietary omega-6/omega-3 (ω-6/ω-3) polyunsaturated fatty acid (PUFAs) ratios on the bone marrow fatty acids level, plasma biomarkers of bone metabolism, and minerals content in bone were evaluated in rabbits. Weanling male and female New Zealand white rabbits were randomly assigned to five groups and fed ad libitum for 100 days on diets containing 70 g/kg different dietary oils which providing the following ω-6/ω-3 ratios: soy bean oil (SBO control, 8.68), sesame oil (SO, 21.75), fish oil (FO, 0.39), DHA algae oil (DHA, 0.63), and DHA and ARA algae oils (DHA/ARA, 0.68). The bone marrow arachidonic (ARA), eicosapentaenoic (EPA), and docosahexaenoic (DHA) fatty acid levels were significantly influenced by and reflected the dietary ω-6/ω-3 ratios fed to rabbits. Rabbits fed on the FO diet maintained a lower ω-6/ω-3 ratio and a higher EPA and DHA levels, those fed on the DHA/ARA diet maintained a lower ω-6/ω-3 ratio and a higher ARA level, while those fed on the SO diet maintained a higher ω-6/ω-3 ratio and a lower ARA level. Plasma alkaline phosphatase (ALP) activity was significantly higher in male and female rabbits fed the DHA/ARA diet compared with those fed the control, SO, FO, or DHA diets. There was a significant main effect of dietary treatment on femur calcium (Ca), phosphorous (P), magnesium (Mg), and zinc (Zn) contents in both genders. This study confirmed that different dietary oil sources with varying ω-6/ω-3 ratios significantly altered the fatty acids level of bone marrow. In addition, the significant elevation in minerals content and the maintenance of optimal Ca/P ratio in bone of DHA/ARA and DHA fed groups beside the significant elevation in ALP activity in the DHA/ARA fed group proved that marine algae oils may be promising dietary sources for promoting bone mineralization and formation, thus improving bone mass during the growth stage.Keywords: arachidonic (ARA), docosahexaenoic (DHA), eicosapentaenoic (EPA), growing rabbits
Procedia PDF Downloads 4856178 The Morphology and Flash Flood Characteristics of the Transboundary Khowai River: A Catchment Scale Analysis
Authors: Jonahid Chakder, Mahfuzul Haque
Abstract:
Flash flood is among the foremost disastrous characteristic hazards which cause hampering within the environment and social orders due to climate change across the world. In Northeastern region of Bangladesh faces severe flash floods regularly, Such, the Khowai river is a flash flood-prone river. But until now, there are no previous studies about the flash flood of this river. Farmlands Building resilience, protection of crops & fish enclosures of wetland in Habiganj Haor areas, regional roads, and business establishments were submerged due to flash floods. The flash floods of the Khowai River are frequent events, which happened in 1988, 1998, 2000, 2007, 2017, and 2019. Therefore, this study tries to analyze Khowai river morphology, Precipitation, Water level, Satellite image, and Catchment characteristics: a catchment scale analysis that helps to comprehend Khowai river flash flood characteristics and factors of influence. From precipitation analysis, the finding outcome disclosed the data about flash flood accurate zones at the Khowai district watershed. The morphological analysis workout from satellite image and find out the consequence of sinuosity and gradient of this river. The sinuosity indicates that the Khowai river is an antecedent and a meandering river and a meandering river can’t influence the flash flood of any region, but other factors respond here. It is understood that the Khowai river catchment elevation analysis from DEM is directly influenced. The left Baramura and Right Atharamura anticline of the Khowai basin watershed reflects a major impact on the stratigraphy as an impermeable clay layer and this consequence the water passes downward with the drainage pattern and Tributary. This drainage system, the gradient of tributary and their runoff, and the confluence of water in the pre-monsoon season rise the Khowai river water level which influences flash floods (within six hours of Precipitation).Keywords: geology, gradient, tributary, drainage, watershed, flash flood
Procedia PDF Downloads 1266177 Spatial Analysis of the Impact of City Developments Degradation of Green Space in Urban Fringe Eastern City of Yogyakarta Year 2005-2010
Authors: Pebri Nurhayati, Rozanah Ahlam Fadiyah
Abstract:
In the development of the city often use rural areas that can not be separated from the change in land use that lead to the degradation of urban green space in the city fringe. In the long run, the degradation of green open space this can impact on the decline of ecological, psychological and public health. Therefore, this research aims to (1) determine the relationship between the parameters of the degradation rate of urban development with green space, (2) develop a spatial model of the impact of urban development on the degradation of green open space with remote sensing techniques and Geographical Information Systems in an integrated manner. This research is a descriptive research with data collection techniques of observation and secondary data . In the data analysis, to interpret the direction of urban development and degradation of green open space is required in 2005-2010 ASTER image with NDVI. Of interpretation will generate two maps, namely maps and map development built land degradation green open space. Secondary data related to the rate of population growth, the level of accessibility, and the main activities of each city map is processed into a population growth rate, the level of accessibility maps, and map the main activities of the town. Each map is used as a parameter to map the degradation of green space and analyzed by non-parametric statistical analysis using Crosstab thus obtained value of C (coefficient contingency). C values were then compared with the Cmaximum to determine the relationship. From this research will be obtained in the form of modeling spatial map of the City Development Impact Degradation Green Space in Urban Fringe eastern city of Yogyakarta 2005-2010. In addition, this research also generate statistical analysis of the test results of each parameter to the degradation of green open space in the Urban Fringe eastern city of Yogyakarta 2005-2010.Keywords: spatial analysis, urban development, degradation of green space, urban fringe
Procedia PDF Downloads 3136176 New Subculture in Social Media
Authors: Maryam Mousivand
Abstract:
Subculture is one of the important concepts in social sciences and the field of cultural studies, which falls under the huge concept of culture. In general, subculture is a kind of movement and experience of collective resistance that is manifested by a population as a reaction against the acceptance of official identities approved by custom and society. Subcultures exist in the virtual world in the new era, and they emerged in various forms, such as the emergence of a subculture under common concepts and interests in the form of sites, channels, and groups of virtual space, which will be discussed in this article.Keywords: subculture, social media, cultural studies, culture
Procedia PDF Downloads 1196175 Distorted Digital Mediated Communication: An Analysis of the Effect of Smartphone on Family Communication in Nigeria
Authors: Peter E. Egielewa
Abstract:
Communication through the smartphone connects people globally. However, since the last 10 years, there has been an increasing shift from the social engagement in the family to the digital mediated communication aided by the smartphone. The traditional family communication had largely been oral and relational, which the smartphone is now digitally mediating. The study employs mixed research method of quantitative and qualitative research design and deploys questionnaire to elicit responses from both parents and children of 50 purposively selected families from five villages in Southern Nigeria that are very active with smartphone use. Based on the Theory of Family Systems, preliminary findings show that the smartphone is becoming an addiction among Nigerian family members and has shifted the dynamics of family communication from relational to digital culture. The research concludes that smartphone use affects family communication negatively and recommends the moderation of smartphone use in the family and the search for alternative platforms for family communication that minimises smartphone addiction.Keywords: digital, distorted communication, family, Nigeria, smartphone
Procedia PDF Downloads 1396174 What Does FDI Inflow Mean for Emerging African Economies?
Authors: E.George, P. Ojeaga, O. Matthew, A. Adekola
Abstract:
Can foreign direct investment (FDI), promote growth in Africa? What does the inflow of investment hold for African emerging economies? Are the determinants of FDI different for different regional blocs in Africa? This study reviews the implication of FDI for different regional blocs in Africa. FDI was found to have a significant effect on growth in North Africa but had no significant effect in East, Southern and West Africa. FDI was also found not to be driving growth in the whole of Africa in a significant manner. The implications of the findings are that even though trade openness seems to be a major factor driving FDI. Poor domestic markets were still preventing many African economies from taking full advantage of the gains from foreign direct investment. The study results could be useful to scholars who study the dynamics surrounding FDI disbursement and strategies on how FDI can drive growth in developing countries.Keywords: Africa, political economy, FDI, regional policy, markets
Procedia PDF Downloads 5746173 Tibial Plateau Fractures During Covid-19 In A Trauma Unit. Impact of Lockdown and The Pressures on the Healthcare Provider
Authors: R. Gwynn, P. Panwalkar, K. Veravalli , M. Tofighi, R. Clement, A. Mofidi
Abstract:
The aim of this study was to access the impact of Covid-19 and lockdown on the incidence, injury pattern, and treatment of tibial plateau fractures in a combined rural and urban population in wales. Methods: Retrospective study was performed to identify tibial plateau fractures in 15-month period of Covid-19 lockdown 15-month period immediately before lockdown. Patient demographics, injury mechanism, injury severity (based on Schatzker classification), and associated injuries, treatment methods, and outcome of fractures in the Covid-19 period was studied. Results: The incidence oftibial plateau fracture was 9 per 100000 during Covid-19, and 8.5 per 100000, and both were similar to previous studies. The average age was 52, and female to male ratio was 1:1 in both control and study group. High energy injury was seen in only 20% of the patients and 35% in the control groups (2=12, p<0025). 14% of the covid-19 population sustained other injuries as opposed 16% in the control group(2=0.09, p>0.95). Lower severity isolated lateral condyle fracturesinjury (Schatzker 1-3) were seen in 40% of fractures this was 60% in the control populations. Higher bicondylar and shaft fractures (Schatzker 5-6) were seen in 60% of the Covid-19 group and 35% in the control groups(2=7.8, p<0.02). Treatment mode was not impacted by Covid-19. The complication rate was low in spite of higher number of complex fractures and the impact of covid-19 pandemic. Conclusion: The associated injuries were similar in spite of a significantly lower mechanism of injury. There were unexpectedly worst tibial plateau fracture based Schatzker classification in the Covid-19 period as compared to the control groups. This was especially relevant for medial condyle and shaft fractures. This was postulated to be caused by reduction in bone density caused by lack of vitamin D and reduction in activity. The treatment mode and outcome was not impacted by the impact of Covid-19 on care for tibial plateau fractures.Keywords: Covid-19, knee, tibial plateau fracture, trauma
Procedia PDF Downloads 1256172 Interacting with Multi-Scale Structures of Online Political Debates by Visualizing Phylomemies
Authors: Quentin Lobbe, David Chavalarias, Alexandre Delanoe
Abstract:
The ICT revolution has given birth to an unprecedented world of digital traces and has impacted a wide number of knowledge-driven domains such as science, education or policy making. Nowadays, we are daily fueled by unlimited flows of articles, blogs, messages, tweets, etc. The internet itself can thus be considered as an unsteady hyper-textual environment where websites emerge and expand every day. But there are structures inside knowledge. A given text can always be studied in relation to others or in light of a specific socio-cultural context. By way of their textual traces, human beings are calling each other out: hypertext citations, retweets, vocabulary similarity, etc. We are in fact the architects of a giant web of elements of knowledge whose structures and shapes convey their own information. The global shapes of these digital traces represent a source of collective knowledge and the question of their visualization remains an opened challenge. How can we explore, browse and interact with such shapes? In order to navigate across these growing constellations of words and texts, interdisciplinary innovations are emerging at the crossroad between fields of social and computational sciences. In particular, complex systems approaches make it now possible to reconstruct the hidden structures of textual knowledge by means of multi-scale objects of research such as semantic maps and phylomemies. The phylomemy reconstruction is a generic method related to the co-word analysis framework. Phylomemies aim to reveal the temporal dynamics of large corpora of textual contents by performing inter-temporal matching on extracted knowledge domains in order to identify their conceptual lineages. This study aims to address the question of visualizing the global shapes of online political discussions related to the French presidential and legislative elections of 2017. We aim to build phylomemies on top of a dedicated collection of thousands of French political tweets enriched with archived contemporary news web articles. Our goal is to reconstruct the temporal evolution of online debates fueled by each political community during the elections. To that end, we want to introduce an iterative data exploration methodology implemented and tested within the free software Gargantext. There we combine synchronic and diachronic axis of visualization to reveal the dynamics of our corpora of tweets and web pages as well as their inner syntagmatic and paradigmatic relationships. In doing so, we aim to provide researchers with innovative methodological means to explore online semantic landscapes in a collaborative and reflective way.Keywords: online political debate, French election, hyper-text, phylomemy
Procedia PDF Downloads 1866171 Controlling Excitons Complexes in Two Dimensional MoS₂ Monolayers
Authors: Arslan Usman, Abdul Sattar, Hamid Latif, Afshan Ashfaq, Muhammad Rafique, Martin Koch
Abstract:
Two-dimensional materials have promising applications in optoelectronic and photonics; MoS₂ is the pioneer 2D material in the family of transition metal dichalcogenides. Its optical, optoelectronic, and structural properties are of practical importance along with its exciton dynamics. Exciton, along with exciton complexes, plays a vital role in realizing quantum devices. MoS₂ monolayers were synthesized using chemical vapour deposition (CVD) technique on SiO₂ and hBN substrates. Photoluminescence spectroscopy (PL) was used to identify the monolayer, which also reflects the substrate based peak broadening due to screening effects. In-plane and out of plane characteristic vibrational modes E¹₂g and A₁g, respectively, were detected in a different configuration on the substrate. The B-excitons and trions showed a dominant feature at low temperatures due to electron-phonon coupling effects, whereas their energies are separated by 100 meV.Keywords: 2D materials, photoluminescence, AFM, excitons
Procedia PDF Downloads 1456170 Numerical Simulation on Two Components Particles Flow in Fluidized Bed
Authors: Wang Heng, Zhong Zhaoping, Guo Feihong, Wang Jia, Wang Xiaoyi
Abstract:
Flow of gas and particles in fluidized beds is complex and chaotic, which is difficult to measure and analyze by experiments. Some bed materials with bad fluidized performance always fluidize with fluidized medium. The material and the fluidized medium are different in many properties such as density, size and shape. These factors make the dynamic process more complex and the experiment research more limited. Numerical simulation is an efficient way to describe the process of gas-solid flow in fluidized bed. One of the most popular numerical simulation methods is CFD-DEM, i.e., computational fluid dynamics-discrete element method. The shapes of particles are always simplified as sphere in most researches. Although sphere-shaped particles make the calculation of particle uncomplicated, the effects of different shapes are disregarded. However, in practical applications, the two-component systems in fluidized bed also contain sphere particles and non-sphere particles. Therefore, it is needed to study the two component flow of sphere particles and non-sphere particles. In this paper, the flows of mixing were simulated as the flow of molding biomass particles and quartz in fluidized bad. The integrated model was built on an Eulerian–Lagrangian approach which was improved to suit the non-sphere particles. The constructed methods of cylinder-shaped particles were different when it came to different numerical methods. Each cylinder-shaped particle was constructed as an agglomerate of fictitious small particles in CFD part, which means the small fictitious particles gathered but not combined with each other. The diameter of a fictitious particle d_fic and its solid volume fraction inside a cylinder-shaped particle α_fic, which is called the fictitious volume fraction, are introduced to modify the drag coefficient β by introducing the volume fraction of the cylinder-shaped particles α_cld and sphere-shaped particles α_sph. In a computational cell, the void ε, can be expressed as ε=1-〖α_cld α〗_fic-α_sph. The Ergun equation and the Wen and Yu equation were used to calculate β. While in DEM method, cylinder-shaped particles were built by multi-sphere method, in which small sphere element merged with each other. Soft sphere model was using to get the connect force between particles. The total connect force of cylinder-shaped particle was calculated as the sum of the small sphere particles’ forces. The model (size=1×0.15×0.032 mm3) contained 420000 sphere-shaped particles (diameter=0.8 mm, density=1350 kg/m3) and 60 cylinder-shaped particles (diameter=10 mm, length=10 mm, density=2650 kg/m3). Each cylinder-shaped particle was constructed by 2072 small sphere-shaped particles (d=0.8 mm) in CFD mesh and 768 sphere-shaped particles (d=3 mm) in DEM mesh. The length of CFD and DEM cells are 1 mm and 2 mm. Superficial gas velocity was changed in different models as 1.0 m/s, 1.5 m/s, 2.0m/s. The results of simulation were compared with the experimental results. The movements of particles were regularly as fountain. The effect of superficial gas velocity on cylinder-shaped particles was stronger than that of sphere-shaped particles. The result proved this present work provided a effective approach to simulation the flow of two component particles.Keywords: computational fluid dynamics, discrete element method, fluidized bed, multiphase flow
Procedia PDF Downloads 3266169 Beyond Objectification: Moderation Analysis of Trauma and Overexcitability Dynamics in Women
Authors: Ritika Chaturvedi
Abstract:
Introduction: Sexual objectification, characterized by the reduction of an individual to a mere object of sexual desire, remains a pervasive societal issue with profound repercussions on individual well-being. Such experiences, often rooted in systemic and cultural norms, have long-lasting implications for mental and emotional health. This study aims to explore the intricate relationship between experiences of sexual objectification and insidious trauma, further investigating the potential moderating effects of overexcitabilities as proposed by Dabrowski's theory of positive disintegration. Methodology: The research involved a comprehensive cohort of 204 women, spanning ages from 18 to 65 years. Participants were tasked with completing self-administered questionnaires designed to capture their experiences with sexual objectification. Additionally, the questionnaire assessed symptoms indicative of insidious trauma and explored overexcitabilities across five distinct domains: emotional, intellectual, psychomotor, sensory, and imaginational. Employing advanced statistical techniques, including multiple regression and moderation analysis, the study sought to decipher the intricate interplay among these variables. Findings: The study's results revealed a compelling positive correlation between experiences of sexual objectification and the onset of symptoms indicative of insidious trauma. This correlation underscores the profound and detrimental effects of sexual objectification on an individual's psychological well-being. Interestingly, the moderation analyses introduced a nuanced understanding, highlighting the differential roles of various overexcitabilities. Specifically, emotional, intellectual, and sensual overexcitabilities were found to exacerbate trauma symptomatology. In contrast, psychomotor overexcitability emerged as a protective factor, demonstrating a mitigating influence on the relationship between sexual objectification and trauma. Implications: The study's findings hold significant implications for a diverse array of stakeholders, encompassing mental health practitioners, educators, policymakers, and advocacy groups. The identified moderating effects of overexcitabilities emphasize the need for tailored interventions that consider individual differences in coping and resilience mechanisms. By recognizing the pivotal role of overexcitabilities in modulating the traumatic consequences of sexual objectification, this research advocates for the development of more nuanced and targeted support frameworks. Moreover, the study underscores the importance of continued research endeavors to unravel the intricate mechanisms and dynamics underpinning these relationships. Such endeavors are crucial for fostering the evolution of informed, evidence-based interventions and strategies aimed at mitigating the adverse effects of sexual objectification and promoting holistic well-being.Keywords: sexual objectification, insidious trauma, emotional overexcitability, intellectual overexcitability, sensual overexcitability, psychomotor overexcitability, imaginational overexcitability
Procedia PDF Downloads 466168 Using Urban Conversion to Green Public Space as a Tool to Generate Urban Change: Case of Seoul
Authors: Rachida Benabbou, Sang Hun Park, Hee Chung Lee
Abstract:
The world’s population is increasing with unprecedented speed, leading to fast growing urbanization pace. Cities since the Industrial revolution had evolved to fit the growing demand on infrastructure, roads, transportation, and housing. Through this evolution, cities had grown into grey, polluted, and vehicle-oriented urban areas with a significant lack of green spaces. Consequently, we ended up with low quality of life for citizens. Therefore, many cities, nowadays, are revising the way we think urbanism and try to grow into more livable and citizen-friendly, by creating change from the inside out. Thus, cities are trying to bring back nature in its crowded grey centers and regenerate many urban areas as green public spaces not only as a way to give new breath to the city, but also as a way to create change either in the environmental, social and economic levels. The city of Seoul is one of the fast growing global cities. Its population is over 12 million and it is expected to continue to grow to a point where the quality of life may seriously deteriorate. As most green areas in Seoul are located in the suburbs in form of mountains, the city’s urban areas suffer from lack of accessible green spaces in a walking distance. Understanding the gravity and consequences of this issue, Seoul city is undergoing major changes. Many of its projects are oriented to be green public spaces where citizens can enjoy the public life in healthy outdoors. The aim of this paper is to explore the results of urban conversions into green public spaces. Starting with different locations, nature, size, and scale, these conversions can lead to significant change in the surrounding areas, thus can be used as an efficient tool of regeneration for urban areas. Through a comparative analysis of three different types of urban conversions projects in the city of Seoul, we try to show the positive urban influence of the outcomes, in order to encourage cities to use green spaces as a strategic tool for urban regeneration and redevelopment.Keywords: urban conversion, green public space, change, urban regeneration
Procedia PDF Downloads 3056167 Association of 1565C/T Polymorphism of Integrin Beta-3 (ITGB3) Gene and Increased Risk for Myocardial Infarction in Patients with Premature Coronary Artery Disease among Iranian Population
Authors: Mehrdad Sheikhvatan, Mohammad Ali Boroumand, Mehrdad Behmanesh, Shayan Ziaee
Abstract:
Contradictory results have been obtained regarding the role of integrin, beta 3 (ITGB3) gene polymorphisms in occurrence of acute myocardial infarction (MI) in patients with coronary artery disease (CAD). Hence, we aimed to assess the association between 1565C/T polymorphism of ITGB3 gene and increased risk for acute MI in patients who suffered premature CAD in Iranian population. Our prospective study included 1000 patients (492 men and 508 women aged 21 to 55 years) referred to Tehran Heart center during a period of four years from 2008 to 2011 with the final diagnosis of premature CAD and classified into two groups with history of MI (n = 461) and without of MI (n = 539). The polymorphism variants were determined by PCR-RFLP technique by entering 10% of randomized samples and then genotyping of the polymorphism was also conducted by High Resolution Melting (HRM) method. Among study samples, 640 were followed with a median follow-up time 45.74 months for determining association of long-term major adverse cardiac events (MACE) and genotypes of polymorphisms. There was no significant difference in the frequency of 1565C/T polymorphism between the MI and non-MI groups. The frequency of wild genotype was 69.2% and 72.2%, the frequency of homozygous genotype was 21.3% and 18.4%, and the frequency of mutant genotype was 9.5% and 9.5%, respectively (p=0.505). Results were also similar when adjusted for covariates in a multivariate logistic regression model. No significant difference was also found in total-MACE free survival rate between the patients with different genotypes of 1565C/T polymorphism in both MI and non-MI group. The carriage of the 1565C/T polymorphism of ITGB3 gene seems unlikely to be a significant risk factor for the development of MI in Iranian patients with premature CAD. The presence of this ITGB3 gene polymorphism may not also predict long-term cardiac events.Keywords: coronary artery disease, myocardial infarction, gene, integrin, beta 3, polymorphism
Procedia PDF Downloads 3996166 Brake Force Distribution in Passenger Cars
Authors: Boukhris Lahouari, Bouchetara Mostefa
Abstract:
The active safety of a vehicle is mainly influenced by the properties of the installed braking system. With the increase in road traffic density and travel speeds, increasingly stringent requirements are placed on the vehicle's behaviour during braking. The achievable decelerations are limited by the physical aspect characterized by the coefficient of friction between the tires and the ground. As a result, it follows that an optimized distribution of braking forces becomes necessary for a better use of friction coefficients. This objective could only be achieved if sufficient knowledge is available on the theory of vehicle dynamics during braking and on current standards for the approval of braking systems. These will facilitate the development of a braking force calculation algorithm that will enable an optimized distribution of braking forces to be achieved. Operating safety is conditioned by the requirements of efficiency, progressiveness, regularity or fidelity of a braking system without obviously neglecting the recommendations imposed by the legislator.Keywords: brake force distribution, distribution diagram, friction coefficient, brake by wire
Procedia PDF Downloads 796165 Clinical Profile, Evaluation, Management and Visual Outcome of Idiopathic Intracranial Hypertension in a Neuro-Ophthalmology Clinic in Jeddah, Saudi Arabia
Authors: Rahaf Mandura
Abstract:
Background: Idiopathic intracranial hypertension (IIH) is a disorder with elevated intracranial pressure (ICP) more than 250 mm H₂O, without evidence of meningeal inflammation, space-occupying lesion, or venous thrombosis. The aim of this research is to study the clinical profile, evaluation, management, and visual outcome in a hospital-based population of IIH cases in Jeddah. Methodology: This is a retrospective observational study that included the medical records of all patients referred to neuro-ophthalmology service for evaluation of papilledema. The medical records have been reviewed from October 2018 to February 2020 at Jeddah Eye Hospital (JEH), Saudi Arabia. A total of fifty-one patients presented with papilledema in the studied period. Forty-seven patients met our inclusion criteria and were included in the study. Results: Most of the patients were females (43, 91.5%) with a mean age of presentation of 30.83±11.40 years. The most common presenting symptom was headache (40 patients, 85.1%), followed by transient visual obscuration (20 patients, 42.6%), and reduced visual acuity (15 patients, 31.9%). All 47 patients were started on medical treatment with oral acetazolamide with four patients (8.5%) shifted to topiramate because of the lack of response or intolerance to acetazolamide while four patients (8.5%) underwent lumbar-peritoneal shunt because of inadequate control of the disease despite the treatment with medical therapy. For both eyes, the change in visual acuity across all assessment points was statistically significant. Nevertheless, there were no significant changes in the visual field findings among all of the compared assessment points. Conclusion: The present study has shown that IIH-related papilledema is common in young female patients with headaches, transient visual obscurations and reduced visual acuity. Those are the commonest symptoms in our IIH population. Medical treatment of IIH is significantly efficacious and should be considered in order to enhance the prognosis of IIH-related complications. Therefore, the visual status should be frequently monitored for these patients.Keywords: idiopathic intracranial hypertension, intracranial hypertension, papilledema, headache
Procedia PDF Downloads 1916164 The Epidemiological Study on Prevalence of Giardia lamblia among Children in Esfahan City of Iran
Authors: Shahla Rostamirad
Abstract:
Purpose: Giardiasis is a widespread infection in humans caused by Giardia lamblia. The prevalence of this parasite among children in Isfahan of Iran is unknown. This study intended to estimate Giardia lamblia infection prevalence and identify possible associated risk factors in a healthy pediatric population living in the Isfahan, a metropolitan city of Iran. Methods: Between September 2010 and March 2012, 1448 stool sample from children with clinical manifestation that refer to clinical lab in Isfahan city for stool examination were collected and analyzed. About 1218 samples were positive for parasitic disease. All of samples were examined and diagnosed by direct examination and formalin-ether concentration of stools. Results: A total of 1218 positive cases were analyzed in this study. The findings showed that 92.5% of patients were infected by protozoa and 7.5 percent with helminth infection. The highest and lowest rate of infection belongs to Giardia lamblia and Entamoeba histolytica with 75% and 1.1%, respectively. Other infection cases were included of Blastocystys hominis 9.9%, E. coli 6.5%, H. nana 1.3%, Enterobious vermicolaris 4% and Ascaris lumbricoides 2.2% percent. The population studied revealed a gender distribution of 53.2% male and 46.8% female. Age distribution was 57.3% between 0-5 years and 42.7% between 6-15 years.The prevalence was higher among children aged 0-5 years (57.8%), than among older children (42.2%). Conclusion: The prevalence of protozoan parasite, especially Giardiasis, in children residing in the region of Isfahan is high. Several risk factors were associated with this prevalence and highlight the importance of parents' education and sanitation conditions in the children's well being. The association between Giardia lamblia and H. pylori seems an important issue deserving further investigation in order to promote prevention or treatment strategies. Other risk factor include presence of Helicobacter pylori infection, living in houses with own drainage system and reported household, pet contact, especially with cat and dog.Keywords: Giardia duodenalis, prevalence, risk factors, children, Isfahan, Iran
Procedia PDF Downloads 3776163 Microbial Quality Assessment of Indian White Shrimp, Penaeus Indicus from Southwest Bangladesh
Authors: Saima Sharif Nilla, Mahmudur Rahman Khan, Anisur Rahman Khan, Ghulam Mustafa1
Abstract:
The microbial quality of Indian white shrimp (Peneaus indicus) from Bagerhat, Khulna and Satkhira of southwest Bangladesh was assessed where the parameters varied with different sources and the quality was found to be poor for Satkhira shrimp samples. Shrimp samples in fresh condition were collected to perform the microbial assessment and 10 pathogenic isolates for antibiotic sensitivity test to 12 antibiotics. The results show that total bacterial count of all the samples were beyond the acceptable limit 105 cfu/g. In case of total coliform and E. coli density, no substantial difference (p<0.5) was found between the different shrimp samples from different districts and also high quantity of TC exceeding the limit (>102 cfu/g) proves the poor quality of shrimp. The FC abundance found in shrimps of Bagerhat and Satkhira was similar and significantly higher (p<0.5) than that of Khulna samples. No significant difference (p<0.5) was found among the high density of Salmonella-Shigella, Vibrio spp., and Staphylococcus spp. of the shrimp samples from the source places. In case of antibiotic sensitivity patterns, all of them were resistant to ampicillin, Penicillin and sensitive to kanamycin. Most of the isolates were frequently sensitive to ciprofloxacin and streptomycin in the sensitivity test. In case of nutritional composition, no significant difference (t-test, p<0.05) was found among protein, lipid, moisture and ash contents of shrimp samples. The findings prove that shrimp under this study was more or less contaminated and samples from Satkhira were highly privileged with food borne pathogens which confirmed the unhygienic condition of the shrimp farms as well as the presence of antibiotic resistance bacteria in shrimp fish supposed to threat food safety and deteriorate the export quality.Keywords: food borne pathogens, satkhira, penaeus indicus, antibiotic sensitivity, southwest Bangladesh, food safety
Procedia PDF Downloads 7066162 An Assessment of Health Hazards in Urban Communities: A Study of Spatial-Temporal Variations of Dengue Epidemic in Colombo, Sri Lanka
Authors: U. Thisara G. Perera, C. M. Kanchana N. K. Chandrasekara
Abstract:
Dengue is an epidemic which is spread by Aedes Egyptai and Aedes Albopictus mosquitoes. The cases of dengue show a dramatic growth rate of the epidemic in urban and semi urban areas spatially in tropical and sub-tropical regions of the world. Incidence of dengue has become a prominent reason for hospitalization and deaths in Asian countries, including Sri Lanka. During the last decade the dengue epidemic began to spread from urban to semi-urban and then to rural settings of the country. The highest number of dengue infected patients was recorded in Sri Lanka in the year 2016 and the highest number of patients was identified in Colombo district. Together with the commercial, industrial, and other supporting services, the district suffers from rapid urbanization and high population density. Thus, drainage and waste disposal patterns of the people in this area exert an additional pressure to the environment. The district is situated in the wet zone and thus low lying lands constitute the largest portion of the district. This situation additionally facilitates mosquito breeding sites. Therefore, the purpose of the present study was to assess the spatial and temporal distribution patterns of dengue epidemic in Kolonnawa MOH area (Medical Officer of Health) in the district of Colombo. The study was carried out using 615 recorded dengue cases in Kollonnawa MOH area during the south east monsoon season from May to September 2016. The Moran’s I and Kernel density estimation were used as analytical methods. The analysis of data was accomplished through the integrated use of ArcGIS 10.1 software packages along with Microsoft Excel analytical tool. Field observation was also carried out for verification purposes during the study period. Results of the Moran’s I index indicates that the spatial distribution of dengue cases showed a cluster distribution pattern across the area. Kernel density estimation emphasis that dengue cases are high where the population has gathered, especially in areas comprising housing schemes. Results of the Kernel Density estimation further discloses that hot spots of dengue epidemic are located in the western half of the Kolonnawa MOH area, which is close to the Colombo municipal boundary and there is a significant relationship with high population density and unplanned urban land use practices. Results of the field observation confirm that the drainage systems in these areas function poorly and careless waste disposal methods of the people further encourage mosquito breeding sites. This situation has evolved harmfully from a public health issue to a social problem, which ultimately impacts on the economy and social lives of the country.Keywords: Dengue epidemic, health hazards, Kernel density, Moran’s I, Sri Lanka
Procedia PDF Downloads 3006161 Prevalence of Gastro-Intestinal Helminthes of Farm Animals by Coprological Examination
Authors: Mohammad Saleh Al-Aboody
Abstract:
In the present study 442 fecal samples from cattle, buffaloes, and sheep for contamination with helminthes. Samples were examined from 171 cattle, 128 buffaloes, and 143 sheep. The testing, during the period from May 2014 to April 2015, showed that 81 out of 171cattle were positive for helminthes infection (47.3%), with the rate of infection higher in females (55%) than in males (40%). In buffaloes, 41 of 128 tested were positive, a 32% rate of infection. Again, the infection rate was higher in females (47%) than in males (22%). In sheep, the rate of infection was highest of all three species. The results showed that, the infection rate among cattle were 50.3 % and Trichostrongyle species were the predominant parasites among both cattle and buffaloes. The prevalence rate was much higher in females than males. Regarding seasonal dynamics the highest infection rates with helminthes reported was in spring season.Keywords: helminthes, prevalence, ruminants, trichostrongyle
Procedia PDF Downloads 3776160 Three Dimensional Computational Fluid Dynamics Simulation of Wall Condensation inside Inclined Tubes
Authors: Amirhosein Moonesi Shabestary, Eckhard Krepper, Dirk Lucas
Abstract:
The current PhD project comprises CFD-modeling and simulation of condensation and heat transfer inside horizontal pipes. Condensation plays an important role in emergency cooling systems of reactors. The emergency cooling system consists of inclined horizontal pipes which are immersed in a tank of subcooled water. In the case of an accident the water level in the core is decreasing, steam comes in the emergency pipes, and due to the subcooled water around the pipe, this steam will start to condense. These horizontal pipes act as a strong heat sink which is responsible for a quick depressurization of the reactor core when any accident happens. This project is defined in order to model all these processes which happening in the emergency cooling systems. The most focus of the project is on detection of different morphologies such as annular flow, stratified flow, slug flow and plug flow. This project is an ongoing project which has been started 1 year ago in Helmholtz Zentrum Dresden Rossendorf (HZDR), Fluid Dynamics department. In HZDR most in cooperation with ANSYS different models are developed for modeling multiphase flows. Inhomogeneous MUSIG model considers the bubble size distribution and is used for modeling small-scaled dispersed gas phase. AIAD (Algebraic Interfacial Area Density Model) is developed for detection of the local morphology and corresponding switch between them. The recent model is GENTOP combines both concepts. GENTOP is able to simulate co-existing large-scaled (continuous) and small-scaled (polydispersed) structures. All these models are validated for adiabatic cases without any phase change. Therefore, the start point of the current PhD project is using the available models and trying to integrate phase transition and wall condensing models into them. In order to simplify the idea of condensation inside horizontal tubes, 3 steps have been defined. The first step is the investigation of condensation inside a horizontal tube by considering only direct contact condensation (DCC) and neglect wall condensation. Therefore, the inlet of the pipe is considered to be annular flow. In this step, AIAD model is used in order to detect the interface. The second step is the extension of the model to consider wall condensation as well which is closer to the reality. In this step, the inlet is pure steam, and due to the wall condensation, a liquid film occurs near the wall which leads to annular flow. The last step will be modeling of different morphologies which are occurring inside the tube during the condensation via using GENTOP model. By using GENTOP, the dispersed phase is able to be considered and simulated. Finally, the results of the simulations will be validated by experimental data which will be available also in HZDR.Keywords: wall condensation, direct contact condensation, AIAD model, morphology detection
Procedia PDF Downloads 3046159 Sliding Mode Control of Autonomous Underwater Vehicles
Authors: Ahmad Forouzantabar, Mohammad Azadi, Alireza Alesaadi
Abstract:
This paper describes a sliding mode controller for autonomous underwater vehicles (AUVs). The dynamic of AUV model is highly nonlinear because of many factors, such as hydrodynamic drag, damping, and lift forces, Coriolis and centripetal forces, gravity and buoyancy forces, as well as forces from thruster. To address these difficulties, a nonlinear sliding mode controller is designed to approximate the nonlinear dynamics of AUV and improve trajectory tracking. Moreover, the proposed controller can profoundly attenuate the effects of uncertainties and external disturbances in the closed-loop system. Using the Lyapunov theory the boundedness of AUV tracking errors and the stability of the proposed control system are also guaranteed. Numerical simulation studies of an AUV are included to illustrate the effectiveness of the presented approach.Keywords: lyapunov stability, autonomous underwater vehicle, sliding mode controller, electronics engineering
Procedia PDF Downloads 6126158 Regional Dynamics of Innovation and Entrepreneurship in the Optics and Photonics Industry
Authors: Mustafa İlhan Akbaş, Özlem Garibay, Ivan Garibay
Abstract:
The economic entities in innovation ecosystems form various industry clusters, in which they compete and cooperate to survive and grow. Within a successful and stable industry cluster, the entities acquire different roles that complement each other in the system. The universities and research centers have been accepted to have a critical role in these systems for the creation and development of innovations. However, the real effect of research institutions on regional economic growth is difficult to assess. In this paper, we present our approach for the identification of the impact of research activities on the regional entrepreneurship for a specific high-tech industry: optics and photonics. The optics and photonics has been defined as an enabling industry, which combines the high-tech photonics technology with the developing optics industry. The recent literature suggests that the growth of optics and photonics firms depends on three important factors: the embedded regional specializations in the labor market, the research and development infrastructure, and a dynamic small firm network capable of absorbing new technologies, products and processes. Therefore, the role of each factor and the dynamics among them must be understood to identify the requirements of the entrepreneurship activities in optics and photonics industry. There are three main contributions of our approach. The recent studies show that the innovation in optics and photonics industry is mostly located around metropolitan areas. There are also studies mentioning the importance of research center locations and universities in the regional development of optics and photonics industry. These studies are mostly limited with the number of patents received within a short period of time or some limited survey results. Therefore the first contribution of our approach is conducting a comprehensive analysis for the state and recent history of the photonics and optics research in the US. For this purpose, both the research centers specialized in optics and photonics and the related research groups in various departments of institutions (e.g. Electrical Engineering, Materials Science) are identified and a geographical study of their locations is presented. The second contribution of the paper is the analysis of regional entrepreneurship activities in optics and photonics in recent years. We use the membership data of the International Society for Optics and Photonics (SPIE) and the regional photonics clusters to identify the optics and photonics companies in the US. Then the profiles and activities of these companies are gathered by extracting and integrating the related data from the National Establishment Time Series (NETS) database, ES-202 database and the data sets from the regional photonics clusters. The number of start-ups, their employee numbers and sales are some examples of the extracted data for the industry. Our third contribution is the utilization of collected data to investigate the impact of research institutions on the regional optics and photonics industry growth and entrepreneurship. In this analysis, the regional and periodical conditions of the overall market are taken into consideration while discovering and quantifying the statistical correlations.Keywords: entrepreneurship, industrial clusters, optics, photonics, emerging industries, research centers
Procedia PDF Downloads 4076157 Feasibility Study on the Application of Waste Materials for Production of Sustainable Asphalt Mixtures
Authors: Farzaneh Tahmoorian, Bijan Samali, John Yeaman
Abstract:
Road networks are expanding all over the world during the past few decades to meet the increasing freight volumes created by the population growth and industrial development. At the same time, the rate of generation of solid wastes in the society is increasing with the population growth, technological development, and changes in the lifestyle of people. Thus, the management of solid wastes has become an acute problem. Accordingly, there is a need for greater efficiency in the construction and maintenance of road networks, in reducing the overall cost, especially the utilization of natural materials such as aggregates. An efficient means to reduce construction and maintenance costs of road networks is to replace natural (virgin) materials by secondary, recycled materials. Recycling will also help to reduce pressure on landfills and demand for extraction of natural virgin materials thus ensuring sustainability. Application of solid wastes in asphalt layer reduces not only environmental issues associated with waste disposal but also the demand for virgin materials which will subsequently result in sustainability. Therefore, this research aims to investigate the feasibility of the application of some of the waste materials such as glass, construction and demolition wastes, etc. as alternative materials in pavement construction, particularly flexible pavements. To this end, various combination of different waste materials in certain percentages is considered in designing the asphalt mixture. One of the goals of this research is to determine the optimum percentage of all these materials in the mixture. This is done through a series of tests to evaluate the volumetric properties and resilient modulus of the mixture. The information and data collected from these tests are used to select the adequate samples for further assessment through advanced tests such as triaxial dynamic test and fatigue test, in order to investigate the asphalt mixture resistance to permanent deformation and also cracking. This paper presents the results of these investigations on the application of waste materials in asphalt mixture for production of a sustainable asphalt mix.Keywords: asphalt, glass, pavement, recycled aggregate, sustainability
Procedia PDF Downloads 2366156 Monitoring Spatial Distribution of Blue-Green Algae Blooms with Underwater Drones
Authors: R. L. P. De Lima, F. C. B. Boogaard, R. E. De Graaf-Van Dinther
Abstract:
Blue-green algae blooms (cyanobacteria) is currently a relevant ecological problem that is being addressed by most water authorities in the Netherlands. These can affect recreation areas by originating unpleasant smells and toxins that can poison humans and animals (e.g. fish, ducks, dogs). Contamination events usually take place during summer months, and their frequency is increasing with climate change. Traditional monitoring of this bacteria is expensive, labor-intensive and provides only limited (point sampling) information about the spatial distribution of algae concentrations. Recently, a novel handheld sensor allowed water authorities to quicken their algae surveying and alarm systems. This study converted the mentioned algae sensor into a mobile platform, by combining it with an underwater remotely operated vehicle (also equipped with other sensors and cameras). This provides a spatial visualization (mapping) of algae concentrations variations within the area covered with the drone, and also in depth. Measurements took place in different locations in the Netherlands: i) lake with thick silt layers at the bottom, very eutrophic former bottom of the sea and frequent / intense mowing regime; ii) outlet of waste water into large reservoir; iii) urban canal system. Results allowed to identify probable dominant causes of blooms (i), provide recommendations for the placement of an outlet, day-night differences in algae behavior (ii), or the highlight / pinpoint higher algae concentration areas (iii). Although further research is still needed to fully characterize these processes and to optimize the measuring tool (underwater drone developments / improvements), the method here presented can already provide valuable information about algae behavior and spatial / temporal variability and shows potential as an efficient monitoring system.Keywords: blue-green algae, cyanobacteria, underwater drones / ROV / AUV, water quality monitoring
Procedia PDF Downloads 2076155 Assessment of the Risks of Environmental Factors on the Health of Kazakhstan Cities in Promoting the Sustainable Development Goals
Authors: Rassima Salimbayeva, Kaliash Stamkulova, Gulparshyn Satbayeva
Abstract:
In order to adapt projects to promote Sustainable Development Goal 11. «Ensuring openness, security, resilience and environmental sustainability of cities and human settlements», presented in the UN Concept, it is necessary to assess the environmental sustainability of cities. From the analysis of the problems of sustainable development of cities in Kazakhstan, it can be seen that the industrial past created a typical range of problems -transport, housing, environment, and, importantly, image. Currently, the issue of air pollution in cities whose economies are dominated by one industry or company should be studied in more detail at the level of projects. In this research, using ecological, economic, and social indicators of five single-industry towns of the Karaganda region of Kazakhstan, an assessment of the risks of the negative impact of environmental factors on the health of the population was carried out, including by paying special attention to air quality. In order to investigate the relationship between the structure of industry, environmental pressure, and environmental sustainability of resource-oriented cities, an analysis of the main components was carried out to measure the structure of industry, environmental stress, and environmental sustainability of single-industry towns. It has been established that in resource-based cities, economic growth mainly depends on the development of one main industry, which primarily depends on local natural resources. Empirical results show that the regional structure of industry has a significant negative impact on the environmental sustainability of cities, in particular on the health of the population living in them. The paper complements the study of the theory of urban sustainability and clarifies the relationship between industrial structure and environmental pressure on health safety and environmental sustainability of cities and towns, which is crucial for further promoting the "green" development of single-industry towns based on natural resources.Keywords: public health risks, urban sustainability, suspended solids, single-industry towns, atmospheric air, environmental pollution
Procedia PDF Downloads 146154 Analyzing the Evolution and Maturation of Bitcoin Improvement Proposals
Authors: Rodrigo Costa, Thomas Mazzuchi, Shahram Sarkani
Abstract:
This study analyzes the evolution of Bitcoin Improvement Proposals (BIPs), the self-governing mechanism that enables updates to the Bitcoin protocol. By modeling BIP submission frequencies with a Negative Binomial distribution and detecting change points with the Pelt Rupture model, we identify three distinct intervals of proposal activity, suggesting shifts in development priorities over time. Long-term growth patterns, captured by Gompertz and Weibull models, indicate an S-shaped trend in cumulative BIP counts, pointing toward a maturation phase in Bitcoin’s protocol. Our findings suggest that Bitcoin may be entering a stable stage, with fewer fundamental changes and more incremental enhancements. This trend highlights the need for further research into BIP content and more studies into its dynamics to better understand decentralized protocol governance and maturation.Keywords: bitcoin improvement proposals, innovation management, change point detection, systems modeling, simulation
Procedia PDF Downloads 76153 Linkage between a Plant-based Diet and Visual Impairment: A Systematic Review and Meta-Analysis
Authors: Cristina Cirone, Katrina Cirone, Monali S. Malvankar-Mehta
Abstract:
Purpose: An increased risk of visual impairment has been observed in individuals lacking a balanced diet. The purpose of this paper is to characterize the relationship between plant-based diets and specific ocular outcomes among adults. Design: Systematic review and meta-analysis. Methods: This systematic review and meta-analysis were conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement guidelines. The databases MEDLINE, EMBASE, Cochrane, and PubMed, were systematically searched up until May 27, 2021. Of the 503 articles independently screened by two reviewers, 21 were included in this review. Quality assessment and data extraction were performed by both reviewers. Meta-analysis was conducted using STATA 15.0. Fixed-effect and random-effect models were computed based on heterogeneity. Results: A total of 503 studies were identified which then underwent duplicate removal and a title and abstract screen. The remaining 61 studies underwent a full-text screen, 21 progressed to data extraction and fifteen were included in the quantitative analysis. Meta-analysis indicated that regular consumption of fish (OR = 0.70; CI: [0.62-0.79]) and skim milk, poultry, and non-meat animal products (OR = 0.70; CI: [0.61-0.79]) is positively correlated with a reduced risk of visual impairment (age-related macular degeneration, age-related maculopathy, cataract development, and central geographic atrophy) among adults. Consumption of red meat [OR = 1.41; CI: [1.07-1.86]) is associated with an increased risk of visual impairment. Conclusion: Overall, a pescatarian diet is associated with the most favorable visual outcomes among adults, while the consumption of red meat appears to negatively impact vision. Results suggest a need for more local and government-led interventions promoting a healthy and balanced diet.Keywords: plant-based diet, pescatarian diet, visual impairment, systematic review, meta-analysis
Procedia PDF Downloads 1856152 A Spatial Repetitive Controller Applied to an Aeroelastic Model for Wind Turbines
Authors: Riccardo Fratini, Riccardo Santini, Jacopo Serafini, Massimo Gennaretti, Stefano Panzieri
Abstract:
This paper presents a nonlinear differential model, for a three-bladed horizontal axis wind turbine (HAWT) suited for control applications. It is based on a 8-dofs, lumped parameters structural dynamics coupled with a quasi-steady sectional aerodynamics. In particular, using the Euler-Lagrange Equation (Energetic Variation approach), the authors derive, and successively validate, such model. For the derivation of the aerodynamic model, the Greenbergs theory, an extension of the theory proposed by Theodorsen to the case of thin airfoils undergoing pulsating flows, is used. Specifically, in this work, the authors restricted that theory under the hypothesis of low perturbation reduced frequency k, which causes the lift deficiency function C(k) to be real and equal to 1. Furthermore, the expressions of the aerodynamic loads are obtained using the quasi-steady strip theory (Hodges and Ormiston), as a function of the chordwise and normal components of relative velocity between flow and airfoil Ut, Up, their derivatives, and section angular velocity ε˙. For the validation of the proposed model, the authors carried out open and closed-loop simulations of a 5 MW HAWT, characterized by radius R =61.5 m and by mean chord c = 3 m, with a nominal angular velocity Ωn = 1.266rad/sec. The first analysis performed is the steady state solution, where a uniform wind Vw = 11.4 m/s is considered and a collective pitch angle θ = 0.88◦ is imposed. During this step, the authors noticed that the proposed model is intrinsically periodic due to the effect of the wind and of the gravitational force. In order to reject this periodic trend in the model dynamics, the authors propose a collective repetitive control algorithm coupled with a PD controller. In particular, when the reference command to be tracked and/or the disturbance to be rejected are periodic signals with a fixed period, the repetitive control strategies can be applied due to their high precision, simple implementation and little performance dependency on system parameters. The functional scheme of a repetitive controller is quite simple and, given a periodic reference command, is composed of a control block Crc(s) usually added to an existing feedback control system. The control block contains and a free time-delay system eτs in a positive feedback loop, and a low-pass filter q(s). It should be noticed that, while the time delay term reduces the stability margin, on the other hand the low pass filter is added to ensure stability. It is worth noting that, in this work, the authors propose a phase shifting for the controller and the delay system has been modified as e^(−(T−γk)), where T is the period of the signal and γk is a phase shifting of k samples of the same periodic signal. It should be noticed that, the phase shifting technique is particularly useful in non-minimum phase systems, such as flexible structures. In fact, using the phase shifting, the iterative algorithm could reach the convergence also at high frequencies. Notice that, in our case study, the shifting of k samples depends both on the rotor angular velocity Ω and on the rotor azimuth angle Ψ: we refer to this controller as a spatial repetitive controller. The collective repetitive controller has also been coupled with a C(s) = PD(s), in order to dampen oscillations of the blades. The performance of the spatial repetitive controller is compared with an industrial PI controller. In particular, starting from wind speed velocity Vw = 11.4 m/s the controller is asked to maintain the nominal angular velocity Ωn = 1.266rad/s after an instantaneous increase of wind speed (Vw = 15 m/s). Then, a purely periodic external disturbance is introduced in order to stress the capabilities of the repetitive controller. The results of the simulations show that, contrary to a simple PI controller, the spatial repetitive-PD controller has the capability to reject both external disturbances and periodic trend in the model dynamics. Finally, the nominal value of the angular velocity is reached, in accordance with results obtained with commercial software for a turbine of the same type.Keywords: wind turbines, aeroelasticity, repetitive control, periodic systems
Procedia PDF Downloads 2496151 Entrepreneurship Education: A Panacea for Entrepreneurial Intention of University Undergraduates in Ogun State, Nigeria
Authors: Adedayo Racheal Agbonna
Abstract:
The rising level of graduate unemployment in Nigeria has brought about the introduction of entrepreneurship education as a career option for self–reliance and self-employment. Sequel to this, it is important to have an understanding of the determining factors of entrepreneurial intention. Therefore this research empirically investigated the influence of entrepreneurship education on entrepreneurial intention of undergraduate students of selected universities in Ogun State, Nigeria. The study is significant to researchers, university policy makers, and the government. Survey research design was adopted in the study. The population consisted of 17,659 final year undergraduate students universities in Ogun State. The study adopted stratified and random sampling technique. The table of sample size determination was used to determine the sample size for this study at 95% confidence level and 5% margin error to arrive at a sample size of 1877 respondents. The elements of population were 400 level students of the selected universities. A structured questionnaire titled 'Entrepreneurship Education and students’ Entrepreneurial intention' was administered. The result of the reliability test had the following values 0.716, 0.907 and 0.949 for infrastructure, perceived university support, and entrepreneurial intention respectively. In the same vein, from the construct validity test, the following values were obtained 0.711, 0.663 and 0.759 for infrastructure, perceived university support and entrepreneurial intention respectively. Findings of this study revealed that each of the entrepreneurship education variables significantly affected intention University infrastructure B= -1.200, R²=0.679, F (₁,₁₈₇₅) = 3958.345, P < 0.05) Perceived University Support B= -1.027, R²=0.502, F(₁,₁₈₇₅) = 1924.612, P < 0.05). The perception of respondents in public university and private university on entrepreneurship education have a statistically significant difference [F(₁,₁₈₇₅) = 134.614, p < 0.05) α F(₁,₁₈₇₅) = 363.439]. The study concluded that entrepreneurship education positively influenced entrepreneurial intention of undergraduate students in Ogun State, Nigeria. Also, university infrastructure and perceived university support have negative and significant effect on entrepreneurial intention. The study recommended that to promote entrepreneurial intention of university undergraduate students, infrastructures and the university support that can arouse entrepreneurial intention of students should be put in place.Keywords: entrepreneurship education, entrepreneurial intention, perceived university support, university infrastructure
Procedia PDF Downloads 235