Search results for: high dose rate brachytherapy
13530 Prediction of Ionic Liquid Densities Using a Corresponding State Correlation
Authors: Khashayar Nasrifar
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Ionic liquids (ILs) exhibit particular properties exemplified by extremely low vapor pressure and high thermal stability. The properties of ILs can be tailored by proper selection of cations and anions. As such, ILs are appealing as potential solvents to substitute traditional solvents with high vapor pressure. One of the IL properties required in chemical and process design is density. In developing corresponding state liquid density correlations, scaling hypothesis is often used. The hypothesis expresses the temperature dependence of saturated liquid densities near the vapor-liquid critical point as a function of reduced temperature. Extending the temperature dependence, several successful correlations were developed to accurately correlate the densities of normal liquids from the triple point to a critical point. Applying mixing rules, the liquid density correlations are extended to liquid mixtures as well. ILs are not molecular liquids, and they are not classified among normal liquids either. Also, ILs are often used where the condition is far from equilibrium. Nevertheless, in calculating the properties of ILs, the use of corresponding state correlations would be useful if no experimental data were available. With well-known generalized saturated liquid density correlations, the accuracy in predicting the density of ILs is not that good. An average error of 4-5% should be expected. In this work, a data bank was compiled. A simplified and concise corresponding state saturated liquid density correlation is proposed by phenomena-logically modifying reduced temperature using the temperature-dependence for an interacting parameter of the Soave-Redlich-Kwong equation of state. This modification improves the temperature dependence of the developed correlation. Parametrization was next performed to optimize the three global parameters of the correlation. The correlation was then applied to the ILs in our data bank with satisfactory predictions. The correlation of IL density applied at 0.1 MPa and was tested with an average uncertainty of around 2%. No adjustable parameter was used. The critical temperature, critical volume, and acentric factor were all required. Methods to extend the predictions to higher pressures (200 MPa) were also devised. Compared to other methods, this correlation was found more accurate. This work also presents the chronological order of developing such correlations dealing with ILs. The pros and cons are also expressed.Keywords: correlation, corresponding state principle, ionic liquid, density
Procedia PDF Downloads 12213529 Numerical Study of Jet Impingement Heat Transfer
Authors: A. M. Tiara, Sudipto Chakraborty, S. K. Pal
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Impinging jets and their different configurations are important from the viewpoint of the fluid flow characteristics and their influence on heat transfer from metal surfaces due to their complex flow characteristics. Such flow characteristics results in highly variable heat transfer from the surface, resulting in varying cooling rates which affects the mechanical properties including hardness and strength. The overall objective of the current research is to conduct a fundamental investigation of the heat transfer mechanisms for an impinging coolant jet. Numerical simulation of the cooling process gives a detailed analysis of the different parameters involved even though employing Computational Fluid Dynamics (CFD) to simulate the real time process, being a relatively new research area, poses many challenges. The heat transfer mechanism in the current research is actuated by jet cooling. The computational tool used in the ongoing research for simulation of the cooling process is ANSYS Workbench software. The temperature and heat flux distribution along the steel strip with the effect of various flow parameters on the heat transfer rate can be observed in addition to determination of the jet impingement patterns, which is the major aim of the present analysis. Modelling both jet and air atomized cooling techniques using CFD methodology and validating with those obtained experimentally- including trial and error with different models and comparison of cooling rates from both the techniques have been included in this work. Finally some concluding remarks are made that identify some gaps in the available literature that have influenced the path of the current investigation.Keywords: CFD, heat transfer, impinging jets, numerical simulation
Procedia PDF Downloads 23013528 Co-Gasification Process for Green and Blue Hydrogen Production: Innovative Process Development, Economic Analysis, and Exergy Assessment
Authors: Yousaf Ayub
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A co-gasification process, which involves the utilization of both biomass and plastic waste, has been developed to enable the production of blue and green hydrogen. To support this endeavor, an Aspen Plus simulation model has been meticulously created, and sustainability analysis is being conducted, focusing on economic viability, energy efficiency, advanced exergy considerations, and exergoeconomics evaluations. In terms of economic analysis, the process has demonstrated strong economic sustainability, as evidenced by an internal rate of return (IRR) of 8% at a process efficiency level of 70%. At present, the process has the potential to generate approximately 1100 kWh of electric power, with any excess electricity, beyond meeting the process requirements, capable of being harnessed for green hydrogen production via an alkaline electrolysis cell (AEC). This surplus electricity translates to a potential daily hydrogen production of around 200 kg. The exergy analysis of the model highlights that the gasifier component exhibits the lowest exergy efficiency, resulting in the highest energy losses, amounting to approximately 40%. Additionally, advanced exergy analysis findings pinpoint the gasifier as the primary source of exergy destruction, totaling around 9000 kW, with associated exergoeconomics costs amounting to 6500 $/h. Consequently, improving the gasifier's performance is a critical focal point for enhancing the overall sustainability of the process, encompassing energy, exergy, and economic considerations.Keywords: blue hydrogen, green hydrogen, co-gasification, waste valorization, exergy analysis
Procedia PDF Downloads 5213527 Preparation and Characterization of Biosorbent from Cactus (Opuntia ficus-indica) cladodes and its Application for Dye Removal from Aqueous Solution
Authors: Manisha Choudhary, Sudarsan Neogi
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Malachite green (MG), an organic basic dye, has been widely used for the dyeing purpose, as well as a fungicide and antiseptic in aquaculture industry to control fish parasites and disease. However, MG has now turned out to be an extremely controversial compound due to its adverse impact on living beings. Due to high toxicity, proper treatment of wastewater containing MG is utmost important. Among different available technologies, adsorption process is one of the most efficient and cost-effective treatment method due to its simplicity of design, ease of operation and regeneration of used materials. Nonetheless, commercial activated carbon is expensive leading the researchers to focus on utilizing natural resources. In the present work, a species of cactus, Opuntia ficus-indica (OFI), was used to develop a highly efficient, low-cost powdered activated carbon by chemical activation using NaOH. The biosorbent was characterized by Fourier-transform infrared spectroscopy, field emission scanning electron microscope, energy-dispersive X-ray spectroscopy, Brunauer–Emmett–Teller (BET) and X-ray diffraction analysis. Batch adsorption studies were performed to remove MG from an aqueous solution as a function of contact time, initial solution pH, initial dye concentration, biosorbent dosages, the presence of salt and temperature. By increasing the initial dye concentration from 100 to 500 mg/l, adsorption capacity increased from 165.45 to 831.58 mg/g. The adsorption kinetics followed the pseudo-second-order model and the chemisorption mechanisms were revealed. The electrostatic attractions and chemical interactions were observed between amino and hydroxyl groups of the biosorbent and amine groups of the dye. The adsorption was solely controlled by film diffusion. Different isotherm models were used to fit the adsorption data. The excellent recovery of adsorption efficiency after the regeneration of biosorbent indicated the high potential of this adsorbent to remove MG from aqueous solution and an excellent cost-effective biosorbent for wide application in wastewater treatment.Keywords: adsorption, biosorbent, cactus, malachite green
Procedia PDF Downloads 36413526 Attitudes and Behaviors of Pediatric Residents towards Care for Underserved Children in a Tertiary Government Hospital
Authors: Paul Lawrence Filomeno, John Robert Medina, Anna Lisa Ong-Lim, Leonila Dans
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Introduction: In most hospitals, pediatric residents are part of the frontline team who interacts with medically underserved patients. Despite of these daily encounters, little is known regarding their attitudes and behaviors towards caring for these underserved patients. Objectives: This study measured the pediatric resident physicians’ attitudes and behaviors towards underserved patients and determine its association. Methodology: The study utilized a cross-sectional mixed methodology, combining the use of a self-administered questionnaire survey using the Learner’s Needs Assessment tool, measuring both attitudes and behaviors towards the underserved. This is followed by a focus group discussion (FGD) involving a sample of residents at the Philippine General Hospital. Results: The response rate was 100% among 62 residents. Overall, 78% of pediatric residents acknowledged the issues of medically underserved to be very important. Volunteerism (behaviors) was only 27% during residency, and was projected to be 90% in future practice. No significant association was noted between their attitudes and behaviors. The FGD revealed that factors (i.e. burnout) causes strains in residents towards the underserved. Frustration from genuine concern for the underserved children was apparent. Conclusion: Among PGH pediatric residents, their attitudes and behaviors are noted to be positive towards the underserved. There was no significant correlation noted between having positive attitudes and volunteerism (behaviors) of the residents towards the underserved. Despite this, residents pointed out certain factors (i.e. burnout) that affect their attitudes and behaviors. The study results may serve as the basis for curriculum enhancements tailored to promote resident well-being, molding them to become the ‘5-star pediatricians’ who will genuinely be ready to serve the underserved.Keywords: pediatric residents, attitudes, behaviors, underserved children
Procedia PDF Downloads 21613525 Analysis of the Evolution of Techniques and Review in Cleft Surgery
Authors: Tomaz Oliveira, Rui Medeiros, André Lacerda
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Introduction: Cleft lip and/or palate are the most frequent forms of congenital craniofacial anomalies, affecting mainly the middle third of the face and manifesting by functional and aesthetic changes. Bilateral cleft lip represents a reconstructive surgical challenge, not only for the labial component but also for the associated nasal deformation. Recently, the paradigm of the approach to this pathology has changed, placing the focus on muscle reconstruction and anatomical repositioning of the nasal cartilages in order to obtain the best aesthetic and functional results. The aim of this study is to carry out a systematic review of the surgical approach to bilateral cleft lip, retrospectively analyzing the case series of Plastic Surgery Service at Hospital Santa Maria (Lisbon, Portugal) regarding this pathology, the global assessment of the characteristics of the operated patients and the study of the different surgical approaches and their complications in the last 20 years. Methods: The present work demonstrates a retrospective and descriptive study of patients who underwent at least one reconstructive surgery for cleft lip and/or palate, in the CPRE service of the HSM, in the period between January 1 of 1997 and December 31 of 2017, in which the data relating to 361 individuals were analyzed who, after applying the exclusion criteria, constituted a sample of 212 participants. The variables analyzed were the year of the first surgery, gender, age, type of orofacial cleft, surgical approach, and its complications. Results: There was a higher overall prevalence in males, with cleft lip and cleft palate occurring in greater proportion in males, with the cleft palate being more common in females. The most frequently recorded malformation was cleft lip and palate, which is complete in most cases. Regarding laterality, alterations with a unilateral labial component were the most commonly observed, with the left lip being described as the most affected. It was found that the vast majority of patients underwent primary intervention up to 12 months of age. The surgical techniques used in the approach to this pathology showed an important chronological variation over the years. Discussion: Cleft lip and/or palate is a medical condition associated with high aesthetic and functional morbidity, which requires early treatment in order to optimize the long-term outcome. The existence of a nasolabial component and its respective surgical correction plays a central role in the treatment of this pathology. The high rates of post-surgical complications and unconvincing aesthetic results have motivated an evolution of the surgical technique, increasingly evident in recent years, allowing today to achieve satisfactory aesthetic results, even in bilateral cleft lip with high deformation complexity. The introduction of techniques that favor nasolabial reconstruction based on anatomical principles has been producing increasingly convincing results. The analyzed sample shows that most of the results obtained in this study are, in general, compatible with the results published in the literature. Conclusion: This work showed that the existence of small variations in the surgical technique can bring significant improvements in the functional and aesthetic results in the treatment of bilateral cleft lip.Keywords: cleft lip, palate lip, congenital abnormalities, cranofacial malformations
Procedia PDF Downloads 10613524 Branding and Posting Strategy on Facebook Pages of Higher Education Institutions in Ontario, Canada in 2019-2020: A Quantitative and Qualitative Investigation
Authors: Mai To
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Higher education institutions (HEIs) in Ontario, Canada have invested in social media presence for multiple purposes, such as branding, student’ engagement, and recruitment. To have a full picture of the social media strategy implemented by HEIs in Ontario, Canada, this study used a mixed-method approach to analyze Facebook posts’ characteristics and content. A total of 1789 Facebook posts from September 2019 to April 2020 of six selected HEIs were collected for analysis and coding based on five pre-determined branding positions: Elite, Nurturing, Campus, Outcome, and Commodity. Besides, the study also calculated the engagement rate for each social media practice to measure its effectiveness. The results show that there were not many differences in practices such as posting frequency, length, types, and timing among HEIs. However, the distribution of branding positions and content targeting future students versus current students was varied, although the HEIs employed all five branding positions and targeted the same lists of audiences. Some practices such as evening post for colleges and nurturing branding for universities attracted significantly higher engagement. This study provides a review of current social media practices and branding strategy, as well as informs the practices that can better engage the audiences.Keywords: branding, higher education, social media, student engagement, student recruitment
Procedia PDF Downloads 12213523 Towards Intercultural Competence in EFL Textbook: the Case of ‘New Prospects’
Authors: Kamilia Mebarki
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The promotion of intercultural competence plays an important role in foreign language education. The outcome of intercultural educationalists‟ studies was the adoption of intercultural language learning and a modified version of the Communicative Competence that encompasses an intercultural component enabling language learners to communicate successfully interculturally. Intercultural Competencehas an even more central role in teaching English as a foreign language (EFL) since efforts are critical to preparing learners for intercultural communisation in our global world. In these efforts, EFL learning materials are a crucial stimulus for developing learners’ intercultural competence. There has been a continuous interest in the analysis of EFL textbooks by researcher all over the world. One specific area that has received prominent attention in recent years is a focus on how the cultural content of EFL materials promote intercultural competence. In the Algerian context, research on the locally produced EFL textbooks tend to focus on investigating the linguistic and communicative competence. The cultural content of the materials has not yet been systematically researched. Therefore, this study contributes to filling this gap by evaluating the locally published EFL textbook ‘New Prospects’ used at the high school level as well as investigating teachers’ views and attitudes on the cultural content of ‘New Prospects’ alongside two others locally produced EFL textbooks ‘Getting Through’ and ‘At the Crossroad’ used at high school level. To estimate the textbook’s potential of developing intercultural competence, mixed methods, a combination of quantitative and qualitative data collection, was used in the material evaluation analysed via content analysis and in the survey questionnaire and interview with teachers.Data collection and analysis were supported by the frameworks developed by the researcher for analysing the textbook, questionnaire, and interview. Indeed, based on the literature, three frameworks/ models are developed in this study to analyse, on one hand, the cultural contexts and themes discussed in the material that play an important role in fostering learners’ intercultural awareness. On the other hand, to evaluate the promotion of developing intercultural competence.Keywords: intercultural communication, intercultural communicative competence, intercultural competence, EFL materials
Procedia PDF Downloads 8913522 Shrinkage Evaluation in a Stepped Wax Pattern – a Simulation Approach
Authors: Alok S Chauhan, Sridhar S., Pradyumna R.
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In the process of precision investment casting of turbine hollow blade/vane components, a part of the dimensional deviations observed in the castings can be attributed to the wax pattern. In the process of injection moulding of wax to produce patterns, heated wax shrinks in size during cooling in the die, leading to a reduction in the dimensions of the pattern. Also, flow and thermal induced residual stresses result in shrinkage & warpage of the component after removal from the die, further adding to the deviations. Injection moulding parameters such as wax temperature, flow rate, packing pressure, etc. affect the flow and thermal behavior of the component and hence are directly responsible for the dimensional deviations. There is a need to precisely determine and control these deviations in order to achieve stringent dimensional accuracies imposed on these castings by aerospace standards. Simulation based approaches provide a platform to predict these dimensional deviations without resorting to elaborate experimentation. In the present paper, Moldex3D simulation package has been utilized to analyze the effect of variations in injection temperature, packing pressure and cooling time on the shrinkage behavior of a stepped pattern. Two types of waxes with different rheological properties have been included in the study to gauge the effect of change in wax on the dimensional deviations. A full factorial design of experiments has been configured with these parameters and results of analysis of variance have been presented.Keywords: wax patterns, investment casting, pattern die/mould, wax injection, Moldex3D simulation
Procedia PDF Downloads 36313521 Statistical Characteristics of Code Formula for Design of Concrete Structures
Authors: Inyeol Paik, Ah-Ryang Kim
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In this research, a statistical analysis is carried out to examine the statistical properties of the formula given in the design code for concrete structures. The design formulas of the Korea highway bridge design code - the limit state design method (KHBDC) which is the current national bridge design code and the design code for concrete structures by Korea Concrete Institute (KCI) are applied for the analysis. The safety levels provided by the strength formulas of the design codes are defined based on the probabilistic and statistical theory.KHBDC is a reliability-based design code. The load and resistance factors of this code were calibrated to attain the target reliability index. It is essential to define the statistical properties for the design formulas in this calibration process. In general, the statistical characteristics of a member strength are due to the following three factors. The first is due to the difference between the material strength of the actual construction and that used in the design calculation. The second is the difference between the actual dimensions of the constructed sections and those used in design calculation. The third is the difference between the strength of the actual member and the formula simplified for the design calculation. In this paper, the statistical study is focused on the third difference. The formulas for calculating the shear strength of concrete members are presented in different ways in KHBDC and KCI. In this study, the statistical properties of design formulas were obtained through comparison with the database which comprises the experimental results from the reference publications. The test specimen was either reinforced with the shear stirrup or not. For an applied database, the bias factor was about 1.12 and the coefficient of variation was about 0.18. By applying the statistical properties of the design formula to the reliability analysis, it is shown that the resistance factors of the current design codes satisfy the target reliability indexes of both codes. Also, the minimum resistance factors of the KHBDC which is written in the material resistance factor format and KCE which is in the member resistance format are obtained and the results are presented. A further research is underway to calibrate the resistance factors of the high strength and high-performance concrete design guide.Keywords: concrete design code, reliability analysis, resistance factor, shear strength, statistical property
Procedia PDF Downloads 31513520 Effects of Magnetization Patterns on Characteristics of Permanent Magnet Linear Synchronous Generator for Wave Energy Converter Applications
Authors: Sung-Won Seo, Jang-Young Choi
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The rare earth magnets used in synchronous generators offer many advantages, including high efficiency, greatly reduced the size, and weight. The permanent magnet linear synchronous generator (PMLSG) allows for direct drive without the need for a mechanical device. Therefore, the PMLSG is well suited to translational applications, such as wave energy converters and free piston energy converters. This manuscript compares the effects of different magnetization patterns on the characteristics of double-sided PMLSGs in slotless stator structures. The Halbach array has a higher flux density in air-gap than the Vertical array, and the advantages of its performance and efficiency are widely known. To verify the advantage of Halbach array, we apply a finite element method (FEM) and analytical method. In general, a FEM and an analytical method are used in the electromagnetic analysis for determining model characteristics, and the FEM is preferable to magnetic field analysis. However, the FEM is often slow and inflexible. On the other hand, the analytical method requires little time and produces accurate analysis of the magnetic field. Therefore, the flux density in air-gap and the Back-EMF can be obtained by FEM. In addition, the results from the analytical method correspond well with the FEM results. The model of the Halbach array reveals less copper loss than the model of the Vertical array, because of the Halbach array’s high output power density. The model of the Vertical array is lower core loss than the model of Halbach array, because of the lower flux density in air-gap. Therefore, the current density in the Vertical model is higher for identical power output. The completed manuscript will include the magnetic field characteristics and structural features of both models, comparing various results, and specific comparative analysis will be presented for the determination of the best model for application in a wave energy converting system.Keywords: wave energy converter, permanent magnet linear synchronous generator, finite element method, analytical method
Procedia PDF Downloads 29313519 The Biofertilizer Effect of Pseudomonas of Salt Soils of the North-West Algerian, Study of Comportment of Bean (Vicia Faba)
Authors: Djoudi Abdelhak, Djibaoui Rachid, Reguieg Yassaad Houcine
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Our study focuses on the identification of some species of Pseudomonas (P4, P5, P7 and P8) isolated from saline soils in northwestern Algeria and the effect of their metabolites on the growth of Alternaria alternata the causative agent of the blight of the bean disease (Vicia faba). We are also interested in stimulating the growth of this plant species in saline conditions (60 mM/l NaCl) and the absence of salts. The analysis focuses on rates of inhibition of mycelial growth of Alternaria alternata strain and the rate of growth of plants inoculated with strains of Pseudomonas expressed by biometrics. According to the results of the in-vitro test, P5 and P8 species and their metabolites showed a significant effect on mycelia growth and production of spores of Alternaria alternata. The in-vivo test shows that the species P8 and P5 were significantly and positively influencing the growth in biometric parameters of the bean in saline and salt-free condition. Inoculation with strain P5 has promoted the growth of the bean in stem height, stem fresh weight and dry weight of stems of 108.59%, 115.28%, 104.33%, respectively, in the presence of salt Inoculation with strain P5 has fostered the growth of the bean stem fresh weight of 112.47% in the presence of salt The effect of Pseudomonas species on the development of Vicia faba and the growth of Alternaria alternata is considering new techniques and methods of biological production and crop protection.Keywords: pseudomonas, vicia faba, alternaria alternata, promoting of plant growth
Procedia PDF Downloads 38813518 Variation in Maternal Mortality in Sidama National Regional State, Southern Ethiopia: A Population Based Cross Sectional Household Survey
Authors: Aschenaki Zerihun Kea, Bernt Lindtjorn, Achamyelesh Gebretsadik, Sven Gudmund Hinderaker
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Introduction: Maternal mortality studies conducted at the national level do not provide the information needed for planning and monitoring health programs at lower administrative levels. The aim of this study was to measure maternal mortality, identify risk factors and district-level variations in Sidama National Regional State, southern Ethiopia. Methods: A cross sectional population-based survey was carried out in households where women reported pregnancy and birth outcomes in the past five years. The study was conducted in the Sidama National Regional State, southern Ethiopia, from July 2019 to May 2020. Multi-stage cluster sampling technique was employed. The outcome variable of the study was maternal mortality. Complex sample logistic regression analysis was applied to assess variables independently associated with maternal mortality. Results: We registered 10602 live births (LB) and 48 maternal deaths, yielding an overall maternal mortality ratio (MMR) of 419; 95% CI: 260-577 per 100,000 LB. Aroresa district had the highest MMR with 1142 (95% CI: 693-1591) per 100,000 LB. Leading causes of death were haemorrhage 21 (41%) and eclampsia 10 (27%). Thirty (59%) mothers died during labour, or within 24 hours after delivery, 25 (47%) died at home and 17 (38%) at a health facility. Mothers who did not have formal education had a higher risk of maternal death (AOR: 4.4; 95% CI: 1.7 – 11.0). The risk of maternal death was higher in districts with a low midwife-to-population ratio (AOR: 2.9; 95% CI: 1.0-8.9). Conclusion: The high maternal mortality with district-level variations in Sidama Region highlights the importance of improving obstetric care and employing targeted interventions in areas with high mortality rates. Due attention should be given to improving access to female education. Additional midwives have to be trained and deployed to improve maternal health services and consequently save the lives of mothers.Keywords: maternal mortality variation, maternal death, Sidama, Ethiopia
Procedia PDF Downloads 6613517 Estimation of Energy Efficiency of Blue Hydrogen Production Onboard of Ships
Authors: Li Chin Law, Epaminondas Mastorakos, Mohd Roslee Othman, Antonis Trakakis
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The paper introduces an alternative concept of carbon capture for shipping by using pre-combustion carbon capture technology (Pre-CCS), which was proven to be less energy intensive than post-combustion carbon capture from the engine exhaust. Energy assessment on amine-based post-combustion CCS on LNG-fuelled ships showed that the energy efficiency of CCS ships reduced from 48% to 36.6%. Then, an energy assessment was carried out to compare the power and heat requirements of the most used hydrogen production methods and carbon capture technologies. Steam methane reformer (SMR) was found to be 20% more energy efficient and achieved a higher methane conversion than auto thermal reaction and methane decomposition. Next, pressure swing adsorber (PSA) has shown a lower energy requirement than membrane separation, cryogenic separation, and amine absorption in pre-combustion carbon capture. Hence, an integrated system combining SMR and PSA (SMR-PSA) with waste heat integration (WHR) was proposed. This optimized SMR-based integrated system has achieved 65% of CO₂ reduction with less than 7-percentage point of energy penalty (41.7% of energy efficiency). Further integration of post-combustion CCS with the SMR-PSA integrated system improved carbon capture rate to 86.3% with 9-percentage points of energy penalty (39% energy efficiency). The proposed system was shown to be able to meet the carbon reduction targets set by International Maritime Organization (IMO) with certain energy penalties.Keywords: shipping, decarbonisation, alternative fuels, low carbon, hydrogen, carbon capture
Procedia PDF Downloads 6913516 Influence of Vocational Guidance Services in Determining the Career Choice of Secondary School Students in Enugu State, Nigeria
Authors: Egbo Anthonia Chinonyelum
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This study was designed to identify the extent of the influence of vocational guidance services on career choice of secondary school students in Enugu State. The study was guided by two research questions and two null hypotheses tested at 0.05 level of significance. A sample of 1,054 respondents made of teachers, students and counsellors drawn from the 34 secondary schools from the six educational zones of Enugu State Nigeria was used for the study. The researcher administered the research instruments generated from the randomly selected senior secondary schools from the six educational zones in Enugu State. The data collected from the respondents were analyzed using mean statistics drawn from the responses of senior secondary school students, counsellor and teacher to the questionnaire item. Four point scale was used to measure the opinion of the respondents, such that after the statistical analysis, those items in the questionnaire that have the mean rate of 2.5 and is of great level of influence on the career choice of students. While questionnaire item with the mean below 2.5 were taken as having little extent of influence on career choice of students. The findings in this work showed that there was little extent on the influence of vocational guidance on career choice, choice of subjects and positive attitude of students towards vocational guidance. Based on the findings the researcher recommended that government and other relevant authorities should help by creating the awareness of vocational guidance programme in Schools.Keywords: vocation, guidance, counselling, services, career, choice
Procedia PDF Downloads 4413515 Decreasing Hepatitis B and Tuberculosis Vaccine Coverage Rates among Neonates in Poland, 2015-2017
Authors: Aneta Nitsch-Osuch, Beata Pawlus, Maria Pawlak
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Introduction: Recently, the number of parents who refuse to vaccinate their children or present so-called hesitant behaviors has increased in many developed countries. The study aimed to analyze the completeness and timeliness of vaccinations against hepatitis B and tuberculosis in neonates in a single maternity hospital in Warsaw (Poland). Material and Methods: We analyzed medical records of children born in the hospital between 1st January 2015 and 31st December 2016 and calculated the proportion of newborns not vaccinated on time. Results: The percentage of unvaccinated newborns was similar in the analyzed years: 7.2% in 2015 and 6.7% in 2016. Parental decisions rather than medical contraindications caused non-immunization (4.3% vs. 2.9% in 2015, and 4.7% vs. 2% in 2016). Most parents refused both vaccinations (81%-84%), whereas 7-8% refused only hep B vaccination, and 9-11% refused alone tuberculosis vaccination. The majority of hesitant parents decided to delay both vaccinations (70-80%), while 10-11% of parents chose to delay only one vaccination (hep B). In consecutive years, an increase in the percentage of parents delaying tuberculosis vaccination was reported (10 vs. 19%). Discussion: The increase in the number of newborns who are not correctly vaccinated just after birth due to their parents' decision should be considered non-gradual, both for hepatitis B and tuberculosis. It is necessary to implement effective educational and informative measures targeted at future parents to reinforce positive attitudes towards vaccinations and to dispel doubts about them among parents who are hesitant.Keywords: hepatitis B, tuberculosis, immunization, new-borns, coverage rate
Procedia PDF Downloads 57313514 Enhancement Production and Development of Hot Dry Rock System by Using Supercritical CO2 as Working Fluid Instead of Water to Advance Indonesia's Geothermal Energy
Authors: Dhara Adhnandya Kumara, Novrizal Novrizal
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Hot Dry Rock (HDR) is one of geothermal energy which is abundant in many provinces in Indonesia. Heat exploitation from HDR would need a method which injects fluid to subsurface to crack the rock and sweep the heat. Water is commonly used as the working fluid but known to be less effective in some ways. The new research found out that Supercritical CO2 (SCCO2) can be used to replace water as the working fluid. By studying heat transfer efficiency, pumping power, and characteristics of the returning fluid, we might decide how effective SCCO2 to replace water as working fluid. The method used to study those parameters quantitatively could be obtained from pre-existing researches which observe the returning fluids from the same reservoir with same pumping power. The result shows that SCCO2 works better than water. For cold and hot SCCO2 has lower density difference than water, this results in higher buoyancy in the system that allows the fluid to circulate with lower pumping power. Besides, lower viscosity of SCCO2 impacts in higher flow rate in circulation. The interaction between SCCO2 and minerals in reservoir could induce dehydration of the minerals and enhancement of rock porosity and permeability. While the dissolution and transportation of minerals by SCCO2 are unlikely to occur because of the nature of SCCO2 as poor solvent, and this will reduce the mineral scaling in the system. Under those conditions, using SCCO2 as working fluid for HDR extraction would give great advantages to advance geothermal energy in Indonesia.Keywords: geothermal, supercritical CO2, injection fluid, hot dry rock
Procedia PDF Downloads 21313513 Genetic Diversity of Mycobacterium bovis and Its Zoonotic Potential in Ethiopia: A Systematic Review
Authors: Begna Tulu, Gobena Ameni
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Understanding the types of Mycobacterium bovis (M. bovis) strains circulating in a country and exploring its zoonotic potential has significant contribution in the effort to design control strategies. The main aim of this study was to review and compile the results of studies conducted on M. bovis genotyping and its zoonotic potential of M. bovis in Ethiopia. A systematic search and review of articles published on M. bovis strains in Ethiopia were made. PubMed and Google Scholar databases were considered for the search while the keywords used were 'Mycobacteria,' 'Mycobacterium bovis,' 'Bovine Tuberculosis' and 'Ethiopia.' Fourteen studies were considered in this review and a total of 31 distinct strains of M. bovis (N=211) were obtained; the most dominant strains were SB0133 (N=62, 29.4%), SB1176 (N=61, 28.9%), and followed by SB0134 and SB1476 each (N=18, 8.5%). The clustering rate of M. bovis strains was found to be 42.0%. On the other hand, 6 strains of M. bovis were reported from human namely; SB0665 (N=4), SB0303 (N=2), SB0982 (N=2), SB0133 (N=1), SB1176 (N=1), and 1 new strain. Similarly, a total of 8 strains (N=13) of M. tuberculosis bacteria were also identified from animal subjects; namely SIT149 (N=3), SIT1 (N=2), SIT1688 (n=2), SIT262 (N=2), SIT53 (N=1), SIT59 (N=1), and one new-Ethiopian strain. The result showed that the genetic diversity of M. bovis strains reported from Ethiopia are less diversified and highly clustered. And also the result underlines that there is an ongoing active transmission of M. bovis and M. tuberculosis between human and animals in Ethiopia because a significant number strains of both type of bacteria were reported from human and animals.Keywords: mycobacterium bovis, Mycobacterium tuberculosis, zoonotic potential, genetic diversity, Ethiopia
Procedia PDF Downloads 12913512 Strategies for the Optimization of Ground Resistance in Large Scale Foundations for Optimum Lightning Protection
Authors: Oibar Martinez, Clara Oliver, Jose Miguel Miranda
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In this paper, we discuss the standard improvements which can be made to reduce the earth resistance in difficult terrains for optimum lightning protection, what are the practical limitations, and how the modeling can be refined for accurate diagnostics and ground resistance minimization. Ground resistance minimization can be made via three different approaches: burying vertical electrodes connected in parallel, burying horizontal conductive plates or meshes, or modifying the own terrain, either by changing the entire terrain material in a large volume or by adding earth-enhancing compounds. The use of vertical electrodes connected in parallel pose several practical limitations. In order to prevent loss of effectiveness, it is necessary to keep a minimum distance between each electrode, which is typically around five times larger than the electrode length. Otherwise, the overlapping of the local equipotential lines around each electrode reduces the efficiency of the configuration. The addition of parallel electrodes reduces the resistance and facilitates the measurement, but the basic parallel resistor formula of circuit theory will always underestimate the final resistance. Numerical simulation of equipotential lines around the electrodes overcomes this limitation. The resistance of a single electrode will always be proportional to the soil resistivity. The electrodes are usually installed with a backfilling material of high conductivity, which increases the effective diameter. However, the improvement is marginal, since the electrode diameter counts in the estimation of the ground resistance via a logarithmic function. Substances that are used for efficient chemical treatment must be environmentally friendly and must feature stability, high hygroscopicity, low corrosivity, and high electrical conductivity. A number of earth enhancement materials are commercially available. Many are comprised of carbon-based materials or clays like bentonite. These materials can also be used as backfilling materials to reduce the resistance of an electrode. Chemical treatment of soil has environmental issues. Some products contain copper sulfate or other copper-based compounds, which may not be environmentally friendly. Carbon-based compounds are relatively inexpensive and they do have very low resistivities, but they also feature corrosion issues. Typically, the carbon can corrode and destroy a copper electrode in around five years. These compounds also have potential environmental concerns. Some earthing enhancement materials contain cement, which, after installation acquire properties that are very close to concrete. This prevents the earthing enhancement material from leaching into the soil. After analyzing different configurations, we conclude that a buried conductive ring with vertical electrodes connected periodically should be the optimum baseline solution for the grounding of a large size structure installed on a large resistivity terrain. In order to show this, a practical example is explained here where we simulate the ground resistance of a conductive ring buried in a terrain with a resistivity in the range of 1 kOhm·m.Keywords: grounding improvements, large scale scientific instrument, lightning risk assessment, lightning standards
Procedia PDF Downloads 12913511 Buddhism and Society: The History and Contribution of Buddhist Education in Taiwan
Authors: Meilee Shen
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Buddhist monks and nuns have changed within the dynamic culture of Taiwan that they find themselves in. The diverse cultures, economic development, and advanced educational levels of the island are all part of this. Buddhist education has become an interesting aspect in the history of Taiwanese Buddhism. In recent years, Buddhists in Taiwan have made significant contributions to both academic and religious studies. This paper will focus on the following questions: What is Buddhist education? How does a Buddhist education change monastic role in Taiwanese Buddhism? Finally, how has Buddhist education benefited Taiwanese society? Research indicates that Buddhist education in Taiwan possesses four features: 1. Master teaching disciple: Buddhist masters teach monastic rules to monastic disciples only. 2. Monastic education: It is mainly focused on Buddhist doctrines and sangha rules. 3. From Buddhist education to secular education: Buddhist studies were introduced into secular educational environments that were the beginning for outsiders to study Buddhism. It also opened a door to recruit young college students to enter the monastery. 4. Academic Buddhist training: Buddhist monks and nuns have begun to study at secular colleges in various programs besides Buddhist studies. In recent years, Buddhist colleges and secular universities’ religious studies programs have begun to admit overseas students due to the low birth-rate in Taiwan. Therefore, the relationship between Buddhism and Taiwanese society is dynamic.Keywords: Buddhist college and university in Taiwan, Buddhist education, institutionalization in Taiwanese Buddhism, monastic and secular education, Taiwanese Buddhist monks and nuns
Procedia PDF Downloads 16513510 Processing and Characterization of Oxide Dispersion Strengthened (ODS) Fe-14Cr-3W-0.5Ti-0.3Y₂O₃ (14YWT) Ferritic Steel
Authors: Farha Mizana Shamsudin, Shahidan Radiman, Yusof Abdullah, Nasri Abdul Hamid
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Oxide dispersion strengthened (ODS) ferritic steels are amongst the most promising candidates for large scale structural materials to be applied in next generation fission and fusion nuclear power reactors. This kind of material is relatively stable at high temperature, possess remarkable mechanical properties and comparatively good resistance from neutron radiation damage. The superior performance of ODS ferritic steels over their conventional properties is attributed to the high number density of nano-sized dispersoids that act as nucleation sites and stable sinks for many small helium bubbles resulting from irradiation, and also as pinning points to dislocation movement and grain growth. ODS ferritic steels are usually produced by powder metallurgical routes involving mechanical alloying (MA) process of Y2O3 and pre-alloyed or elemental metallic powders, and then consolidated by hot isostatic pressing (HIP) or hot extrusion (HE) techniques. In this study, Fe-14Cr-3W-0.5Ti-0.3Y₂O₃ (designated as 14YWT) was produced by mechanical alloying process and followed by hot isostatic pressing (HIP) technique. Crystal structure and morphology of this sample were identified and characterized by using X-ray Diffraction (XRD) and field emission scanning electron microscope (FESEM) respectively. The magnetic measurement of this sample at room temperature was carried out by using a vibrating sample magnetometer (VSM). FESEM micrograph revealed a homogeneous microstructure constituted by fine grains of less than 650 nm in size. The ultra-fine dispersoids of size between 5 nm to 19 nm were observed homogeneously distributed within the BCC matrix. The EDS mapping reveals that the dispersoids contain Y-Ti-O nanoclusters and from the magnetization curve plotted by VSM, this sample approaches the behavior of soft ferromagnetic materials. In conclusion, ODS Fe-14Cr-3W-0.5Ti-0.3Y₂O₃ (14YWT) ferritic steel was successfully produced by HIP technique in this present study.Keywords: hot isostatic pressing, magnetization, microstructure, ODS ferritic steel
Procedia PDF Downloads 31113509 Research on Teachers’ Perceptions on the Usability of Classroom Space: Analysis of a Nation-Wide Questionnaire Survey in Japan
Authors: Masayuki Mori
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This study investigates the relationship between teachers’ perceptions of the usability of classroom space and various elements, including both physical and non-physical, of classroom environments. With the introduction of the GIGA School funding program in Japan in 2019, understanding its impact on learning in classroom space is crucial. The program enabled local educational authorities (LEA) to make it possible to provide one PC/tablet for each student of both elementary and junior high schools. Moreover, at the same time, the program also supported LEA to purchase other electronic devices for educational purposes such as electronic whiteboards, large displays, and real image projectors. A nationwide survey was conducted using random sampling methodology among 100 junior high schools to collect data on classroom space. Of those, 60 schools responded to the survey. The survey covered approximately fifty items, including classroom space size, class size, and educational electronic devices owned. After the data compilation, statistical analysis was used to identify correlations between the variables and to explore the extent to which classroom environment elements influenced teachers’ perceptions. Furthermore, decision tree analysis was applied to visualize the causal relationships between the variables. The findings indicate a significant negative correlation between class size and teachers’ evaluation of usability. In addition to the class size, the way students stored their belongings also influenced teachers’ perceptions. As for the placement of educational electronic devices, the installation of a projector produced a small negative correlation with teachers’ perceptions. The study suggests that while the GIGA School funding program is not significantly influential, traditional educational conditions such as class size have a greater impact on teachers’ perceptions of the usability of classroom space. These results highlight the need for awareness and strategies to integrate various elements in designing the learning environment of the classroom for teachers and students to improve their learning experience.Keywords: classroom space, GIGA School, questionnaire survey, teachers’ perceptions
Procedia PDF Downloads 813508 Efficient Frequent Itemset Mining Methods over Real-Time Spatial Big Data
Authors: Hamdi Sana, Emna Bouazizi, Sami Faiz
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In recent years, there is a huge increase in the use of spatio-temporal applications where data and queries are continuously moving. As a result, the need to process real-time spatio-temporal data seems clear and real-time stream data management becomes a hot topic. Sliding window model and frequent itemset mining over dynamic data are the most important problems in the context of data mining. Thus, sliding window model for frequent itemset mining is a widely used model for data stream mining due to its emphasis on recent data and its bounded memory requirement. These methods use the traditional transaction-based sliding window model where the window size is based on a fixed number of transactions. Actually, this model supposes that all transactions have a constant rate which is not suited for real-time applications. And the use of this model in such applications endangers their performance. Based on these observations, this paper relaxes the notion of window size and proposes the use of a timestamp-based sliding window model. In our proposed frequent itemset mining algorithm, support conditions are used to differentiate frequents and infrequent patterns. Thereafter, a tree is developed to incrementally maintain the essential information. We evaluate our contribution. The preliminary results are quite promising.Keywords: real-time spatial big data, frequent itemset, transaction-based sliding window model, timestamp-based sliding window model, weighted frequent patterns, tree, stream query
Procedia PDF Downloads 15013507 3D Interpenetrated Network Based on 1,3-Benzenedicarboxylate and 1,2-Bis(4-Pyridyl) Ethane
Authors: Laura Bravo-García, Gotzone Barandika, Begoña Bazán, M. Karmele Urtiaga, Luis M. Lezama, María I. Arriortua
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Solid coordination networks (SCNs) are materials consisting of metal ions or clusters that are linked by polyfunctional organic ligands and can be designed to form tridimensional frameworks. Their structural features, as for example high surface areas, thermal stability, and in other cases large cavities, have opened a wide range of applications in fields like drug delivery, host-guest chemistry, biomedical imaging, chemical sensing, heterogeneous catalysis and others referred to greenhouse gases storage or even separation. In this sense, the use of polycarboxylate anions and dipyridyl ligands is an effective strategy to produce extended structures with the needed characteristics for these applications. In this context, a novel compound, [Cu4(m-BDC)4(bpa)2DMF]•DMF has been obtained by microwave synthesis, where m-BDC is 1,3-benzenedicarboxylate and bpa 1,2-bis(4-pyridyl)ethane. The crystal structure can be described as a three dimensional framework formed by two equal, interpenetrated networks. Each network consists of two different CuII dimers. Dimer 1 have two coppers with a square pyramidal coordination, and dimer 2 have one with a square pyramidal coordination and other with octahedral one, the last dimer is unique in literature. Therefore, the combination of both type of dimers is unprecedented. Thus, benzenedicarboxylate ligands form sinusoidal chains between the same type of dimers, and also connect both chains forming these layers in the (100) plane. These layers are connected along the [100] direction through the bpa ligand, giving rise to a 3D network with 10 Å2 voids in average. However, the fact that there are two interpenetrated networks results in a significant reduction of the available volume. Structural analysis was carried out by means of single crystal X-ray diffraction and IR spectroscopy. Thermal and magnetic properties have been measured by means of thermogravimetry (TG), X-ray thermodiffractometry (TDX), and electron paramagnetic resonance (EPR). Additionally, CO2 and CH4 high pressure adsorption measurements have been carried out for this compound.Keywords: gas adsorption, interpenetrated networks, magnetic measurements, solid coordination network (SCN), thermal stability
Procedia PDF Downloads 31413506 Polymer Mediated Interaction between Grafted Nanosheets
Authors: Supriya Gupta, Paresh Chokshi
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Polymer-particle interactions can be effectively utilized to produce composites that possess physicochemical properties superior to that of neat polymer. The incorporation of fillers with dimensions comparable to polymer chain size produces composites with extra-ordinary properties owing to very high surface to volume ratio. The dispersion of nanoparticles is achieved by inducing steric repulsion realized by grafting particles with polymeric chains. A comprehensive understanding of the interparticle interaction between these functionalized nanoparticles plays an important role in the synthesis of a stable polymer nanocomposite. With the focus on incorporation of clay sheets in a polymer matrix, we theoretically construct the polymer mediated interparticle potential for two nanosheets grafted with polymeric chains. The self-consistent field theory (SCFT) is employed to obtain the inhomogeneous composition field under equilibrium. Unlike the continuum models, SCFT is built from the microscopic description taking in to account the molecular interactions contributed by both intra- and inter-chain potentials. We present the results of SCFT calculations of the interaction potential curve for two grafted nanosheets immersed in the matrix of polymeric chains of dissimilar chemistry to that of the grafted chains. The interaction potential is repulsive at short separation and shows depletion attraction for moderate separations induced by high grafting density. It is found that the strength of attraction well can be tuned by altering the compatibility between the grafted and the mobile chains. Further, we construct the interaction potential between two nanosheets grafted with diblock copolymers with one of the blocks being chemically identical to the free polymeric chains. The interplay between the enthalpic interaction between the dissimilar species and the entropy of the free chains gives rise to a rich behavior in interaction potential curve obtained for two separate cases of free chains being chemically similar to either the grafted block or the free block of the grafted diblock chains.Keywords: clay nanosheets, polymer brush, polymer nanocomposites, self-consistent field theory
Procedia PDF Downloads 24813505 Spray Drying and Physico-Chemical Microbiological Evaluation of Ethanolic Extracts of Propolis
Authors: David Guillermo Piedrahita Marquez, Hector Suarez Mahecha, Jairo Humberto Lopez
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The propolis are substances obtained from the beehive have an action against pathogens, prooxidant substances and free radicals because of its polyphenols content, this has motivated the use of these compounds in the food and pharmaceutical industries. However, due to their organoleptic properties and their ability to react with other compounds, their application has been limited; therefore, the objective of this research was to propose a mechanism to protect propolis and mitigate side effects granted by its components. To achieve the stated purpose ethanolic extracts of propolis (EEP) from three samples from Santander were obtained and their antioxidant and antimicrobial activity were evaluated in order to choose the extract with the biggest potential. Subsequently mixtures of the extract with maltodextrin were prepared by spray drying varying concentration and temperature, finally the yield, the physicochemical, and antioxidant properties of the products were measured. It was concluded that Socorro propolis was the best for the production of microencapsulated due to their activity against pathogenic strains, for its large percentage of DPPH radical inactivation and for its high phenolic content. In spray drying, the concentration of bioactive had a greater impact than temperature and the conditions set allowed a good performance and the production of particles with high antioxidant potential and little chance of proliferation of microorganisms. Also, it was concluded that the best conditions that allowed us to obtain the best particles were obtained after drying a mixture 1:2 ( EEP: Maltodextrin), besides the concentration is the most important variable in the spray drying process, at the end we obtained particles of different sizes and shape and the uniformity of the surface depend on the temperature. After watching the previously mentioned microparticles by scanning electron microscopy (SEM) it was concluded that most of the particles produced during the spray dry process had a spherical shape and presented agglomerations due to the moisture content of the ethanolic extracts of propolis (EEP), the morphology of the microparticles contributed to the stability of the final product and reduce the loss of total phenolic content.Keywords: spray drying, propolis, maltodextrin, encapsulation, scanning electron microscopy
Procedia PDF Downloads 28413504 Effect of Deep Cryogenic Treatment on Aluminium Alloy Used for Making Heat Exchangers in Automotive HVAC System
Authors: H. Mohit
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In automotive air conditioning system, two heat exchangers are used as evaporator and condenser which are placed inside the bonnet of a car in a compact manner. The dust particles from outside and moisture content produced during the process leads to formation of impure particles on the surface of evaporator coil. But in condenser coil, the impure particles are settling down due to dust from atmosphere. The major problem of the heat exchanger used in automotive air conditioning is leakage of refrigerant due to corrosion. This effect of corrosion will lead to damage on the surface of heat exchanger and leakage of refrigerant from the system. To protect from corrosion, coatings are applied on its surfaces. Nowadays, to improve the corrosion resistance of these heat exchangers, hydrophilic coatings are used, which is very expensive. Cryogenic treatment is one method which involves the treatment of materials below -150 °C using the cryogenic fluid such as liquid nitrogen. In this project work, a study of improvement in corrosion resistance of materials of aluminium alloys of various grades as AA 1100, AA 6061, AA 6063 and AA 2024 that are mainly used for fin and tube heat exchangers in automotive air conditioning system is made. In total, five different processes are selected for these grades of aluminium alloy and various parameters like corrosion rate, dimensional stability, hardness and microstructure are measured. The improvements were observed in these parameters while comparing it with conventional heat treatment process.Keywords: cryogenic treatment, corrosion resistance, dimensional stability, materials science
Procedia PDF Downloads 25413503 An Analytical Approach to Assess and Compare the Vulnerability Risk of Operating Systems
Authors: Pubudu K. Hitigala Kaluarachchilage, Champike Attanayake, Sasith Rajasooriya, Chris P. Tsokos
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Operating system (OS) security is a key component of computer security. Assessing and improving OSs strength to resist against vulnerabilities and attacks is a mandatory requirement given the rate of new vulnerabilities discovered and attacks occurring. Frequency and the number of different kinds of vulnerabilities found in an OS can be considered an index of its information security level. In the present study five mostly used OSs, Microsoft Windows (windows 7, windows 8 and windows 10), Apple’s Mac and Linux are assessed for their discovered vulnerabilities and the risk associated with each. Each discovered and reported vulnerability has an exploitability score assigned in CVSS score of the national vulnerability database. In this study the risk from vulnerabilities in each of the five Operating Systems is compared. Risk Indexes used are developed based on the Markov model to evaluate the risk of each vulnerability. Statistical methodology and underlying mathematical approach is described. Initially, parametric procedures are conducted and measured. There were, however, violations of some statistical assumptions observed. Therefore the need for non-parametric approaches was recognized. 6838 vulnerabilities recorded were considered in the analysis. According to the risk associated with all the vulnerabilities considered, it was found that there is a statistically significant difference among average risk levels for some operating systems, indicating that according to our method some operating systems have been more risk vulnerable than others given the assumptions and limitations. Relevant test results revealing a statistically significant difference in the Risk levels of different OSs are presented.Keywords: cybersecurity, Markov chain, non-parametric analysis, vulnerability, operating system
Procedia PDF Downloads 17813502 Chemical Aging of High-Density Polyethylene (HDPE-100) in Interaction with Aggressive Environment
Authors: Berkas Khaoula, Chaoui Kamel
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Polyethylene (PE) pipes are one of the best options for water and gas transmission networks. The main reason for such a choice is its high-quality performance in service conditions over long periods of time. PE pipes are installed in contact with different soils having various chemical compositions with confirmed aggressiveness. As a result, PE pipe surfaces undergo unwanted oxidation reactions. Usually, the polymer mixture is designed to include some additives, such as anti-oxidants, to inhibit or reduce the degradation effects. Some other additives are intended to increase resistance to the ESC phenomenon associated with polymers (ESC: Environmental Stress Cracking). This situation occurs in contact with aggressive external environments following different contaminations of soil, groundwater and transported fluids. In addition, bacterial activity and other physical or chemical media, such as temperature and humidity, can play an enhancing role. These conditions contribute to modifying the PE pipe structure and degrade its properties during exposure. In this work, the effect of distilled water, sodium hypochlorite (bleach), diluted sulfuric acid (H2SO4) and toluene-methanol (TM) mixture are studied when extruded PE samples are exposed to those environments for given periods. The chosen exposure periods are 7, 14 and 28 days at room temperature and in sealed glass containers. Post-exposure observations and ISO impact tests are presented as a function of time and chemical medium. Water effects are observed to be limited in explaining such use in real applications, whereas the changes in TM and acidic media are very significant. For the TM medium, the polymer toughness increased drastically (from 15.95 kJ/m² up to 32.01 kJ/m²), while sulfuric acid showed a steady augmentation over time. This situation may correspond to a hardening phenomenon of PE increasing its brittleness and its ability for structural degradation because of localized oxidation reactions and changes in crystallinity.Keywords: polyethylene, toluene-methanol mixture, environmental stress cracking, degradation, impact resistance
Procedia PDF Downloads 6913501 Phytochemical Content and Bioactive Properties of Wheat Sprouts
Authors: Jasna Čanadanović-Brunet, Lidija Jevrić, Gordana Ćetković, Vesna Tumbas Šaponjac, Jelena Vulić, Slađana Stajčić
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Wheat contains high amount of nutrients such as dietary fiber, resistant starch, vitamins, minerals and microconstituents, which are building blocks of body tissues, but also help in the prevention of diseases such as cardiovascular disease, cancer and diabetes. Sprouting enhances the nutritional value of whole wheat through biosynthesis of tocopherols, polyphenols and other valuable phytochemicals. Since the nutritional and sensory benefits of germination have been extensively documented, using of sprouted grains in food formulations is becoming a trend in healthy foods. The present work addressed the possibility of using freeze-dried sprouted wheat powder, obtained from spelt-wheat cv. ‘Nirvana’ (Triticum spelta L.) and winter wheat cv. ‘Simonida’ (Triticum aestivum L. ssp. vulgare var. lutescens), as a source of phytochemicals, to improve the functional status of the consumer. The phytochemicals' content (total polyphenols, flavonoids, chlorophylls and carotenoids) and biological activities (antioxidant activity on DPPH radicals and antiinflammatory activity) of sprouted wheat powders were assessed spectrophotometrically. The content of flavonoids (216.52 mg RE/100 g), carotenoids (22.84 mg β-carotene/100 g) and chlorophylls (131.23 mg/100 g), as well as antiinflammatory activity (EC50=3.70 mg/ml) was found to be higher in sprouted spelt-wheat powder, while total polyphenols (607.21 mg GAE/100 g) and antioxidant activity on DDPPH radicals (EC50=0.27 mmol TE/100 g) was found to be higher in sprouted winter wheat powders. Simulation of gastro-intestinal digestion of sprouted wheat powders clearly shows that intestinal digestion caused a higher release of polyphenols than gastric digestion for both samples, which indicates their higher bioavailability in the colon. The results of the current study have shown that wheat sprouts can provide a high content of phytochemicals and considerable bioactivities. Moreover, data reported show that they contain a unique pattern of bioactive molecules, which make these cereal sprouts attractive functional foods for a health-promoting diet.Keywords: wheat, sprouts, phytochemicals, bioactivity
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