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Multi-objective Optimization to Increase Nusselt Number and Reduce Friction Coefficient of Water/Carbon Nanotubes via NSGA II using Response Surface Methodology
Get PDFHeat transfer science is one of the most important and most applied engineering sciences, with the importance of energy management and energy conservation being doubled. Because of their properties, nanofluids have been widely used in various industries, making them particularly important to study. In this paper, the Nusselt number and coefficient of friction with volume fraction ranging from 0 to 0.1 at approximately Reynolds numbers of 200 to 5000 are studied experimentally. Higher thermal conductivity, better stability, lower pressure drop was observed using nanoparticles of solid particles. NSGA II algorithm was used to maximize Nusselt number and minimum friction coefficient by changing temperature and volume fraction of nanoparticles. To obtain Nusselt number and friction coefficient based on the temperature and volume fraction of the nanoparticles, the experimental data response surface methodology was used and with increasing Reynolds number, the Nusselt number increased and the friction coefficient decreased. In order to evaluate the objective functions in the optimization, the response surface methodology is attached to the optimization algorithm. At the end, the Pareto Front and its corresponding optimal points are presented
Pulsed Laser Annealing Effect on Optical and Structural Properties of ZnS/ZnSe Heterostructures
Get PDFStudies of pulsed laser annealing (PLA) on semiconductor thin films were performed to examine changes of the optical and structural parameters due to the laser heat. Thin films of ZnS/ZnSe were deposited on quartz substrates at a pressure of 8.2*10-6 mbar using PVD technique. These thin films were annealed at different laser powers using CO2 pulsed laser. Transmission and reflection spectra were recorded before and after the annealing process. A decrease in the transmission and reflection spectra after annealing is observed. The absorption coefficient, refractive index, damping coefficient and dielectric constant were calculated before and after the annealing process. Changes in the optical parameters are found after the annealing process. The energy band gaps of ZnS and ZnSe have been determined. Upon annealing, an increase in the absorption coefficient is observed which is due to an improvement in the granular nanostructure of the ZnS/ZnSe thin films. XRD patterns of the prepared samples were obtained before and after the annealing procedure and revealed an enhancement in the crystallite structure upon annealing
Influence of Strontium on the Physical, Mechanical and In-Vitro Bioactivity of Glass Ionomer Cements
Get PDFIn this work, we investigated the effects of strontium incorporation in the glass phase of glass ionomer cements (GIC). Three different glass compositions were synthesized with 0, 5, and 10 mol% of SrO addition. GICs were prepared by the addition of 50 wt% polyacrylic acid (PAA) at powder to liquid ratio of 1:1.5. Initial characterization on the cement series was to study their rheological behavior. Cements represented working times between 50-64 seconds and setting times of 356-452 seconds. Rheological results indicated that the addition of strontium decreases the working and setting times of the cements. To analyze the mechanical properties, compressive and flexural strength studies were performed after 1, 10, and 30 days incubation in simulated body fluid (SBF). The compressive strength of the cements increased as a function of incubation time, with the strontium containing compositions showing the highest strength at 34 megapascal (MPa) and after 30 days of incubation. Biaxial flexural strength of the cements was not significantly affected by the composition and maturation time and ranged between 13.4 to 16.3 MPa. In-vitro bioactivity of the cements was analyzed using SBF trials and after 1, 10, and 30 days incubation periods. Strontium containing cements, showed higher solubility with higher amounts of calcium phosphate surface depositions only after 10 days incubation. The elemental identifications of the surface depositions indicated high amounts of Ca, P and Zn are present on the surface of SBF incubated samples
Steganographic Techniques Classification According to Image Format
Get PDFIn this work, we present a classification of steganographic methods applicable to digital images. We also propose a classification of steganographic methods according to the type of image used. We noticed there are no methods that can be applied to all image formats. Each type of image has its characteristics and each steganographic method operates on a precise colorimetric representation. This classification provides an overview of the techniques used for the steganography of digital image
Anti-nutritional Composition, Heavy Metal Content and Mineral Bioavailability of Red Tree Vine (Leea guineensis G. Don) Fruits
Get PDFLeea guineensis G. Don is an evergreen shrub that has been reported to be important in Nigeria due to its medicinal and nutritional uses. However, there is paucity of documented information on the anti-nutritional composition, heavy metal content and mineral bioavailability of L. guineensis whole fruits. Hence, this study investigated the essential minerals, heavy metals and anti-nutritional compositions of L. guineensis whole fruits with a view to assess the quantity, bioavailability of the mineral elements and ultimately the safety of the fruits using standard analytical procedures. The results of phytochemical screening confirmed presence of secondary metabolites in varying quantities. The anti-nutrient contents (mg/100g) were phytates (29530); oxalates (510); saponins (10333); alkaloids (30533) and tannins (53.3). The results of mineral analysis revealed that L. guineensis fruits were rich in essential minerals (mg/100g) like, potassium (493); calcium (200); magnesium (103.3); phosphorus (9.9); zinc (8.5); manganese (5.5) and iron (5.0). The heavy metals concentrations were in the order lead>chromium>nickel>cobalt>cadmium. The values obtained were within the WHO permissible limits for heavy metals in medicinal plants. Meanwhile, the results of molar ratio phytates: Ca (8.97); oxalates: Ca (0.7978) and Ca.phytates:Zn (0.64) were below the suggested critical values indicating the bioavailability of calcium to be high. While phytates: Fe (501.06) and phytates: Zn (348.22) were higher than the critical values indicating poor bioavailability of Fe and Zn. The study therefore suggests that L. guineensis fruits are a good source of phyto-minerals which can be harnessed for nutritional purpose. Also, the anti-nutrient contents in L. guineensis whole fruits should be reduced to a safe level through processing methods (soaking, de-pulping or fermentation) in order to achieve its optimum nutritional or medicinal use
An Observational Review and Analysis of Qualitative Data to Explore the Benefits of Equine Assisted Learning in Improving the Engagement of Adolescents with Complex Learning Needs, within the Educational Setting
Get PDFThe study determined whether Equine Assisted Learning (EAL) acted as a positive influence to improve the engagement of adolescents with complex learning needs, within their educational setting. The past two years has seen a continuous increase in the number of pupils with complex learning needs in the UK, from 1,244,255 in January 2017 to 1,276,215 in January 2018, an increase from 14.4% to 14.6%. These increasing figures provide a clear rationale for the requirement for a greater utilisation of various learning intervention tools, to begin to meet the dynamic needs of these learners. Seven participants engaged in six EAL sessions over six weeks and were involved in an array of unmounted EAL activities. Questionnaires were formulated with reference to the “Student Engagement (SE) Survey” and were presented to both staff and parents at three points throughout the study, along with Carpenters approved engagement scale for staff to complete weekly, within the lesson following the EAL session. Furthermore, observational research was conducted by the researcher to generate a supportive discussion for the obtained results. Through the quantitative data formulated no significant difference was shown, however a moderate positive correlation between the before and after results of staff and parent questionnaires was presented (Staff Questionnaire p =.119366. Parent Questionnaire p = .145547). Further trends also began to emerge, with correlations forming between improved engagement and specific EAL activities, providing a direction for future research
Mechanical Characterization of Nanomaterial Reinforced Aluminum-based Hybrid Nanocomposites
Get PDFNanostructures are viewed as definitive fiber materials as a reinforcement for matrices because of their impressive properties. Because of their phenomenal mechanical properties Carbon nanotubes (CNTs), graphene (GR), and nanodiamond (ND) have made an enormous proportion of intensity in research over the world. Multiwalled carbon nanotubes (MWCNTs), Graphene, and Nano Diamond were utilized as reinforcements for the current work. Nanostructures with their extraordinary strength, minute size, and high aspect ratio were used as reinforcements in commercial-purity Al matrix. These nanocomposites were manufactured by various different routes such as casting and powder metallurgy techniques. Both of these methods are helpful for the preparation of MWCNTs/Al nanocomposites. These nanocomposites were manufactured with various weight fractions of reinforcements and characterized for their mechanical properties and indicated improved properties in contrast with the base Al matrix. Al/MWCNT nanocomposites, Al/MWCNT/GR hybrid nanocomposites and Al/MWCNT/GR/ND hybrid nanocomposites samples were tested for their mechanical properties such as Young’s modulus, percentage elongation yield strength, and ultimate Strength. Mechanical characterization of these prepared composite samples demonstrated improved strength when compared with the casted samples
Moroccan Facebook Visual Narratives and Cultural Production
Get PDFIn this paper, I argue that the creation and circulation of the visual narratives within Facebook groups by Moroccan Facebookers largely entail and substantiate a stronger process of cultural production that has its own logic and praxis. I argue that this process of cultural production has two major facets: an aestheticization of everyday life and promulgation of specific modes of consciousness. Through the aestheticization of everyday life, I posit that Moroccan youth’s acts of cultural production increasingly blur the formal boundaries between the Internet, art, and popular culture; an aspect which fundamentally empowers their creative online input. Through the promulgation of specific modes of consciousness, I argue that the visual narratives attempt to develop and enhance the cultural sensibilities which better champion their perceptions and stances. Taken together, I claim that these major manifestations of the process of cultural production, while being deeply wedded to the Gramscian and Foucauldian perception of power dynamics, set the tone for an underlying struggle over power and meaning-making in the Moroccan society, thus seeking to intervene and exploit the gaps and contradictions in these power dynamics in society
Access to Job Market: Findings from A Venture Development Program for Marginalized Unemployed Youth in Kampala Uganda
Get PDFMajority youths (uneducated/unskilled) in Uganda face challenges identified with unemployment and high-risk practices. An estimated 78 % of Ugandan youth are jobless, need economic capital and life skills. The high rate of unemployment is principally brought about by the absence of employable skills, the lack of capacity of the economy to create as many jobs for the unskilled youth and the ever-increasing population driven by the rural-urban drift. The survey used a mixed methodology where semi-structured questionnaires were used to obtain both quantitative and qualitative primary data using the electronic devices (KoBo Collect software) to conduct the interviews, reaching a total of 770 marginalized youths. Findings from the survey show that vocational skills training, business, career guidance, multi-mixed behavioral and psychological interventions are major determinants of access to the job market for marginalized slum youths. To address youth unemployment, this article underlines the need for interventions that fall outside the regular limits of training and other labor market programs. Numerous young people looking for better jobs and livelihoods are indebted by variables that are not commonly considered in these programs. These incorporate, for instance, lack of access to credit which deters business enterprise. This article has featured solutions important for young people looking for their livelihood in self-employment and entrepreneurship
Given the Time and the Money to Think, Consumers will Rely more on Intuition, Sensations, and Emotions, rather than Rationale, to Decide
Get PDFThe weight of intuitive, sensory, emotional, and rational criteria in consumer decision making has been debated for ages, we could say. The rational model dominated Marketing all through the 20th Century, but on the onset of the new millennium, the case has been made, and strongly so, for a more integrated view of consumer behavior, that allows for, if you will, the rationalization of emotional conducts. In this paper, we present the results of an experiment that shows that purchases are not all that rational, and that –indeed– given the time, and the money to think it through, consumers will paradoxically rely more on their intuition, their emotions and sensations, that is, on feelings over rational criteria, to arrive at a purchase decision. This experiment manipulated two variables, time and money, using a convenience sample of undergraduate students in three classes of Pace University, NY, to apply the same situational questionnaire under two different hypothetical scenarios, where one is similar to the students’ current situation