A PARAMETER IDENTIFICATION APPROACH OF A PEM FUEL CELL STACK USING PARTICLE SWARM OPTIMIZATION

ABSTRACT The fear of fossil fuels depletion as well as the constantly increasing pollution rates motivated most of today's engineers and researchers towards focusing on renewable energies and their applications. Fuel Cells are one of the green technologies that are being explored extensively around the world. The work of this paper was done on the 3kW ElectraGen TM fuel cell system under study for domestic use in the United Arab Emirates (UAE). Several experiments were conducted at different operating points and relatively high ambient temperatures. The experimental I/V characteristics of the system are matched by identifying 13 different modeling parameters using basic fitting. The obtained model is then further optimized using Particle Swarm Optimization (PSO). The resulting model is validated experimentally and was found to highly resemble the system's I/V characteristics yielding less than 1.5 V H ∞ norm of the error

A theoretical first principles computational investigation into the potential of aluminum-doped boron nitride nanotubes for hydrogen storage

Hydrogen storage remains a largely unsolved problem facing the green energy revolution. One approach is physisorption on very high surface area materials incorporating metal atoms. Boron nitride nanotubes (BNNTs) are a promising material for this application as their behaviour is largely independent of the nanoscopic physical features providing a greater degree of tolerance in their synthesis. Aluminum doping has been shown to be a promising approach for carbon nanotubes but has been underexplored for BNNTs. Using first principles density functional theory, the energetics, electronics and structural impacts of aluminum adsorption to both zigzag and armchair polymorphs of BNNTs was investigated along with their potential capacity to adsorb hydrogen. The fine atomic structural and electronic details of these interactions is discussed. We predicted that in an ideal situation, highly aluminum-doped armchair and zigzag BNNTs could adsorb up to 9.4 and 8.6 weight percent hydrogen, well above the United States Department of Energy targets marking these as promising materials worthy of further study

Effect of esomeprazole on maternal serum soluble fms-like tyrosine kinase-1 and endoglin in patients with early-onset preeclampsia

Objective: This study evaluates the effect of esomeprazole on the maternal serum levels of soluble fms-like tyrosine kinase-1 (sFlt-1) and soluble endoglin (sEng) in patients with early-onset preeclampsia.Methods: A randomized, double-blind, placebo-controlled trial was carried out in a tertiary University hospital between March 2018, and September 2019 (Clinical Trials.Gov: NCT03213639). The study included women between 28 and 31+6 weeks gestational age who had been diagnosed as preeclampsia without severe features. They were randomly assigned in a 1:1 ratio into an esomeprazole group, which received esomeprazole 40 mg orally once a day, and a placebo group, which received one placebo tablet daily. Blood samples were obtained to assess levels of serum sFlt-1and sEng using ELISA testing. The primary outcome was the difference between the mean serum level of sFlt-1 and sEng at the start of treatment and at the termination of pregnancy in both groups.Results: Eighty-eight patients were randomly assigned into both groups (44 in each). No statistically significant difference was found in the levels of sFlt-1 between both groups at admission and termination of pregnancy. The number of days of treatment for the esomeprazole group was slightly longer than the placebo group (11.4±9.4 vs. 10.3±6.3 days, P=0.515). No statistically significant difference in the rate of maternal and fetal complications occurred between the two groups. No side effects from the study medications were reported.Conclusions: Esomeprazole, at the dosage used in this study did not effectively lower the serum levels of sFlt-1 and sEng in patients with early-onset preeclampsia. Furthermore, it did not prolong the duration of pregnancy, nor did it decrease maternal or fetal complications

Clinical Characteristics of Non-Intensive Care Unit COVID-19 Patients in Saudi Arabia: A Descriptive Cross-sectional Study

Introduction: The ongoing pandemic of the coronavirus disease 2019 (COVID-19) is a global health concern. It has affected more than 5 million patients worldwide and resulted in an alarming number of deaths globally. While clinical characteristics have been reported elsewhere, data from our region is scarce. We investigated the clinical characteristics of mild to moderate cases of COVID-19 in Saudi Arabia. Methods: This is a descriptive, cross-sectional study. Data of 401 confirmed COVID-19 patients were collected from 22 April 2020 to 21 May 2020 at five tertiary care hospitals in Riyadh, Saudi Arabia. The patients were divided into four groups according to age, Group 1: 0-60 years; and their clinical symptoms were compared. Results: The median (IQR) age in years was 10.5 (1.5-16) in group I, 34 (29-41) in group II, 53 (51-56) in group III, and 66 (61-76) in group IV. Most patients were male (80%, n = 322) and of Arabian or Asian descent. The median length of stay in the hospital was 10 (8-17) days (range 3-42 days). The most common symptoms were cough (53.6%), fever (36.2%), fatigue (26.4%), dyspnea (21.9%), and sore throat (21.9%). Hypertension was the most common underlying comorbidity (14.7%), followed by obesity (11.5%), and diabetes (10%). Hypertensive patients were less likely to present with shortness of breath, cough, sputum, diarrhea, and fever. Conclusion: There was no significant difference in the symptoms among different age groups and comorbidities were mostly seen in the older age group. Interestingly, hypertensive patients were found to have milder symptoms and a shorter length of stay. Further larger collaborative national studies are required to effectively understand clinical characteristics in our part of the world to efficiently manage and control the spread of SARS-CoV-2

Clinical, epidemiological, and laboratory characteristics of mild-to-moderate COVID-19 patients in Saudi Arabia: an observational cohort study

Background Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) emerged from China in December 2019 and has presented as a substantial and serious threat to global health. We aimed to describe the clinical, epidemiological, and laboratory findings of patients in Saudi Arabia infected with SARS-CoV-2 to direct us in helping prevent and treat coronavirus disease 2019 (COVID-19) across Saudi Arabia and around the world. Materials and methods Clinical, epidemiological, laboratory, and radiological characteristics, treatment, and outcomes of pediatric and adult patients in five hospitals in Riyadh, Saudi Arabia, were surveyed in this study. Results 401 patients (mean age 38.16 ± 13.43 years) were identified to be SARS-CoV-2 positive and 80% of cases were male. 160 patients had moderate severity and 241 were mild in severity. The most common signs and symptoms at presentation were cough, fever, fatigue, and shortness of breath. Neutrophil and lymphocyte counts, aspartate aminotransferase, C-reactive protein, and ferritin were higher in the COVID-19 moderate severity patient group. Mild severity patients spent a shorter duration hospitalized and had slightly higher percentages of abnormal CT scans and X-ray imaging. Conclusions This study provides an understanding of the features of non-ICU COVID-19 patients in Saudi Arabia. Further national collaborative studies are needed to streamline screening and treatment procedures for COVID-19

Using Factor Analysis to Generate Clusters of Agile Practices

In this paper, factor analysis is applied on a set of data that was collected to study the effectiveness of 58 different agile practices. The analysis extracted 15 factors; each was associated with a list of practices. These factors with the associated practices can be used as a guide for agile process improvement. Correlations between the extracted factors were calculated, and the significant correlation findings suggested that people who applied iterative and incremental development and quality assurance practices had a high success rate, that communication with the customer was not very popular as it had negative correlations with governance and iterative and incremental development. Also, people who applied governance practices also applied quality assurance practices. Interestingly success rate related negatively with traditional analysis methods such as Gantt chart and detailed requirements specification

Software quality and governance in agile software development

Looking at software engineering from a historical perspective, we can see how software development methodologies have evolved over the past 50 years. Using the right software development methodology with the right settings has always been a challenge. Therefore, there has always been a need for empirical evidence about what worked well and what did not, and what factors affect the different variables of the development process. Probably the most noticeable change to software development methodology in the last 15 years has been the introduction of the word “agile”. As any area matures, there is a need to understand its components and relations, as well as the need of empirical evidence about how well agile methods work in real life settings. In this thesis, we empirically investigate the impact of agile methods on different aspects of quality including product quality, process quality and stakeholders’ satisfaction as well as the different factors that affect these aspects. Quantitative and qualitative research methods were used for this research, including semi-structured interviews and surveys. Quality was studied in two projects that used agile software development. The empirical study showed that both projects were successful with multiple releases, and with improved product quality and stakeholders’ satisfaction. The data analysis produced a list of 13 refined grounded hypotheses out of which 5 were supported throughout the research. One project was studied in-depth by collecting quantitative data about the process used via a newly designed iteration monitor. The iteration monitor was used by the team over three iterations and it helped identify issues and trends within the team in order to improve the process in the following iterations. Data about other organisations collected via surveys was used to generalise the obtained results. A variety of statistical analysis techniques were applied and these suggested that when agile methods have a good impact on quality they also has a good impact on productivity and satisfaction, also when agile methods had good impact on the previous aspects they reduced cost. More importantly, the analysis clustered 58 agile practices into 15 factors including incremental and iterative development, agile quality assurance, and communication. These factors can be used as a guide for agile process improvement. The previous results raised questions about agile project governance, and to answer these questions the agile projects governance survey was conducted. This survey collected 129 responses, and its statistically significant results suggested that: retrospectives are more effective when applied properly as they had more impact when the whole team participated and comments were recorded, that organisation size has a negative relationship with success, and that good practices are related together as when a team does one aspect well, they do all aspects well. Finally, the research results supported the hypotheses: agile software development can produce good quality software, achieve stakeholders’ satisfaction, motivate teams, assures quick and effective response to stakeholder’s requests, and it goes in stages, matures, and improves over time

An Empirical Comparison of Two Agile Projects in the Same Organization

The appearance of Agile methods has been the most noticeable change to software process thinking in the last fifteen years[1]. The main goal of this research is to investigate the quality of Agile projects empirically, in order to help software development organizations increase their understanding of Agile methods, principles and practices. This paper presents a multi-case study that was conducted using semi-structured interviews with two project teams that are using Agile methods within one organization. Our data was analyzed using the constant comparison method. The results are presented to illustrate how the teams adopted Agile methods and a comparison between the two projects is provided. From this it can be concluded that both projects were successful with multiple releases, the quality is generally seem to be as good as other projects in the same organization, the time release is reduced, and the differences between the two projects in terms of communication, the iteration length and the approach to quality, may result from the different team sizes