170 research outputs found
Student’s classroom participation in English language teaching: The case of Gozamen General Secondary School in Grade 10-A
Get PDFStudent’s classroom participation in English language teaching: The case of Gozamen General Secondary School in Grade 10-A
Author / Authors : Atalay Mesfin Aneteneh
Page no. 204-217
Discipline : Education
Script/language : Roman/ English
Category : Research paper/Action research
Keywords: English, Teaching Elementary, Training, Action research
Immunogenicity of the different stages of Eimeria falciformis var. pragensis
No full textThe immunogenicity of the different stages of Eimeria falciformis var. pragensis was evaluated with the indirect fluorescent antibody reaction. Sporozoites, mature asexual stages and merozoites treated with sera from immune mice and with fluorescein-conjugated goat anti-mouse gammaglobulin showed the most intense specific fluorescence. The immature asexual stages and the sexual stages fluoresced weakly, whereas the sporocysts and oocysts did not specifically fluoresce. On the basis of the intensity of the immunofluorescence, the sporozoites and mature asexual generations (merozoites) were considered to be more immunogenic than the immature asexual and the sexual stages. Antibodies against sporocysts and oocysts could not be demonstrated. [AS].RE: 15 ref.; SC: ZA; CA; VE; PA; 0Y; 0V; 0ISource type: Electronic(1) http://upei-resolver.asin-risa.ca?sid=SP:CABI&id=pmid:&id=&issn=0304-4017&isbn=&volume=7&issue=2&spage=87&pages=87-93&date=1980&title=Veterinary%20Parasitology&atitle=Immunogenicity%20of%20the%20different%20stages%20of%20Eimeria%20falciformis%20var.%20pragensis.&aulast=Mesfin&pid=%3Cauthor%3EMesfin%2c%20G%20M%3bBellamy%2c%20J%20E%20C%3C%2Fauthor%3E%3CAN%3E19800878013%3C%2FAN%3E%3CDT%3EJournal%20article%3C%2FDT%3
Retrofitting Options for Natural Gas Liquid (NGL) Fractionation Trains Using the Concept of Single Column Development
No full textAbstractHeat pump assisted distillation (HPAD) system and self-heat recuperation technology (SHRT) have been developed as a result of intensive research to reduce energy consumption of a conventional distillation system. To determine a suitable system for natural gas liquid (NGL) fractionation trains, rigorous analysis and comparative study of several HPAD and SHRT options for the retrofitting of a single column were studied in the present work. The retrofit options considered were vapor compression (VC), mechanical vapor recompression (MVR), thermal vapor recompression (TVR), bottom flashing (BF), side heat exchanger (SHE), intermediate heating and cooling (IHC), self-heat recuperative (SHR) and modified self-heat recuperative (MSHR) distillation. A depropanizer column commonly used in typical NGL plant was selected as a case study. Aspen HYSYS V7.3 was initially used to simulate the eight selected retrofit designs under common sets of criteria. The data from the simulation was then analyzed to determine the best design in term of energy cost reduction. The analysis shows that the MVR gives the highest energy cost reduction of 68.11% as compared to that of the base case (BC) conventional column. It is followed by VC (66.65%), MSHR (64.02%), BF (62.88%), SHR (55.85%), SHE (54.23%), IHC (39.54%), and TVR (12.41%)
A CHANCE-CONSTRAINED APPROACH FOR OPTIMIZATION OF GAS PROCESSING PLANT OPERATION UNDER UNCERTAIN CONDITIONS
Get PDFNatural gas plant operations contribute hugely to the economies of many developed nations that depend on hydrocarbon resources. The plant operation is usually subjected to continuous variations in upstream conditions, such as flow rate, composition, temperature and pressure, which propagate through the plant and affect its stable operations. As a result, decision making for optimal operating conditions of an in-operation plant is a complex problem and it is exacerbated with the changing product specifications and variations in energy supplies. This work presents a new solution method to the problem, which is based on chance constrained optimization method. A deterministic model is initially developed from process simulation using Aspen HYSYS and later converted to a chance constrained model. The probabilistic model is then relaxed to its equivalent deterministic form and solved for optimum solution using GAMS. The optimum solution is determined probabilistically using chance constraints that are held at a user-defined confidence level. Optimal solution is represented graphically as a trade-off between reliability of holding the process constraints and profitability of the plant. Three case studies are presented to demonstrate the new method. Optimization results show that uncertainty of plant parameters significantly affect the economic performance of the plant operation. The solution approach developed in this work is able to increase the reliability of maintaining the profit by more than 95% confidence level. As a result, the risk of constraints violation is reduced from more than 50% using the typical deterministic optimization to less than 5% with the chance constrained optimization approach. In addition, the results from this study indicate that the variation of material flow from the plant inlet has greater impact by more than 85.5% on profit compared to variation from the plant outlet, which is less than 2%. The variations of energy flow affect on profit is mainly changes with confidence level measurement higher than 95%, although material flow uncertainty is more sensitive to profit changes than uncertainty in energy flow. Final computational results also highlight the advantage of the developed chance constrained approach, which combines both the profit and the
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reliability of the process constraints, over “worst case” and two-stage programming approaches. Decisions from the “worst case” approach may reach to more than 99% confidence level which can drastically decrease the profit while the optimal decision from the two-stage programming does not clearly show to how much extent that the profit has been held. The developed solution approach in this work can aid as guidelines to flexible plant operation decision making for the in-operating plant by satisfying all the process constraints at certain confidence level
The effect of material flow uncertainties on the overall economic performance of a typical gas processing plant (GPP) under various upstream conditions
No full textUncertainty is an inherent characteristic of any chemical process plant. It has a profound effect especially for gas processing plant as its feeds are normally originated from different upstream production facilities. Due to this, the plant is usually subject to a continuous variation in upstream conditions, such as temperature, pressure, flow rate and composition. These variations in turn propagate throughout the plant and affect not only the normal operating conditions but also the product specification. This work presents on how the material flow uncertainties from the plant’s inlet and outlet affects the overall economic performance. Accordingly, two chance constrained optimization models were developed by separately taking the uncertainties from both sides of the plant. The developed models were tested using case studies for an existing gas processing plant. The trade-off between profit and reliability of holding the process constraint were analyzed by solving the problem at certain confidence level. The confidence level is a user-defined variable assigned to hold the constraints beginning from 50% to 100%. Result shows that the optimal profit change for material flow uncertainty from the plant inlet is 86%. However, for the uncertainty from the plant outlet, the optimal profit change is only 2% for the same confidence interval [96% - 100%]. The result indicates that uncertainty from the plant inlet has a significant impact in terms of overall economic performance compared to the plant outlet
The effect of material flow uncertainties on the overall economic performance of a typical gas processing plant (GPP) under various upstream conditions
No full textUncertainty is an inherent characteristic of any chemical process plant. It has a profound effect especially for gas processing plant as its feeds are normally originated from different upstream production facilities. Due to this, the plant is usually subject to a continuous variation in upstream conditions, such as temperature, pressure, flow rate and composition. These variations in turn propagate throughout the plant and affect not only the normal operating conditions but also the product specification. This work presents on how the material flow uncertainties from the plant’s inlet and outlet affects the overall economic performance. Accordingly, two chance constrained optimization models were developed by separately taking the uncertainties from both sides of the plant. The developed models were tested using case studies for an existing gas processing plant. The trade-off between profit and reliability of holding the process constraint were analyzed by solving the problem at certain confidence level. The confidence level is a user-defined variable assigned to hold the constraints beginning from 50% to 100%. Result shows that the optimal profit change for material flow uncertainty from the plant inlet is 86%. However, for the uncertainty from the plant outlet, the optimal profit change is only 2% for the same confidence interval [96% - 100%]. The result indicates that uncertainty from the plant inlet has a significant impact in terms of overall economic performance compared to the plant outlet
Assessment of breast self-examination practice and its associated factors among female undergraduate students in Addis Ababa University, Addis Ababa, Ethiopia, 2016
No full textMikiyas Amare Getu, Mesfin Wudu Kassaw, Kenean Getaneh Tlaye, Awet Fitiwi Gebrekiristos Department of Nursing, Faculty of Health Science, Woldia University, Woldia, Ethiopia Background: Breast self-examination (BSE) is a simple, very low-cost, non-invasive early detection method used to detect breast cancer at early stage. It should be done for all women older than 20 years. The aim of this study was to assess BSE practice and associated factors among female undergraduate students in Addis Ababa University, Addis Ababa, Ethiopia. Methods: Institution-based cross-sectional study design was conducted. Departments were selected from College of Business and Economics by using lottery method. A simple random sampling technique was used to select a total of 407 female students from each department. Data were collected by using structured self-administered and pretested questionnaire. Quantitative method was employed. Binary logistic regression and multiple logistic regressions were done to confirm association between variables. Results: The finding of this study revealed that 87 (21.4%) of the study participants have practiced BSE. Of whom, 45 (51.7%) participants perform BSE every month and 9 (10.5%) of the study participants perform BSE at the right time, which is 2–3 days after menstruation. Family history of breast cancer, knowledge, and attitude of BSE were found to be significantly associated with BSE practice. Conclusion: This study revealed that majority of study subjects did not practice BSE. So, It’s recommended that the concerned bodies create awareness around BSE and train students on how to practice BSE. Keywords: practice, breast self-examination, female students, Addis Ababa University, breast cancer, early detection metho
Profit optimization for chemical process plant based on a probabilistic approach by incorporating material flow uncertainties
No full textThis paper reports how the economic performance of a chemical process plant is affected by material flow uncertainties from the plant inlet and outlet. Two chance-constrained optimization models were proposed. The models were tested using case studies of an existing gas processing plant. Profit optimization for the case studies was made with respect to the reliability of holding the process constraints at a certain confidence level [0.5, 1]. The optimal profit change for uncertainty from the plant inlet within the confidence interval [0.96, 1] was 86%. On the other hand, the optimal profit change for uncertainty from the plant outlet was only 2% for the same confidence level interval considered. This suggests that the uncertainty from the plant inlet has a major impact on the overall economic performance of the plant. Sensitivity analysis showed how uncertain parameters from both plant sides can affect the overall profit significantly
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