Mitigation of voltage imbalance in power distribution system using MPC-controlled packed-U-cells converter

Delivering high power quality in single-phase distribution has witnessed more challenges especially with the increased penetration of single-phase distributed generation (DG). This paper proposes a smart solid-state-based transformer, which aims to replace traditional ones, for single-phase distribution laterals, and provide load balancing and protection to the three-phase main feeders, that is based on connecting the single-phase lateral to the three-phase main feeder through a power electronics converter. This converter transfers balanced power from and to the three-phase feeder while automatically regulating the lateral single-phase voltage, hence, assuring high power quality without requiring any transformer on-load tap changer. A 7-level packed-U-cells (PUC) single-phase inverter topology was used to deliver single-phase regulated sinusoidal voltage to the AC loads, and at the same time, it is able to deliver DC power to DC loads. The simulation and hardware-in-the-loop (HIL) results have shown that the proposed topology delivers high power quality for both AC and DC loads under different operating scenarios. Moreover, the converter can play the role of a solid-state protection device coordinated with other up- and downstream protective devices. Finally, this system can be integrated within the smart grid allowing more flexibility for automation and efficient control of the grid. - 2019 The Authors. Energy Science & Engineering published by the Society of Chemical Industry and John Wiley & Sons Ltd.This work was made possible by Qatar University Internal Grant no. QUCP?CENG?EE?15/16?4

Oxidation–reduction potential and sperm DNA fragmentation, and their associations with sperm morphological anomalies amongst fertile and infertile men

Objective: To assess seminal oxidation–reduction potential (ORP) and sperm DNA fragmentation (SDF) in male infertility and their relationships with sperm morphology in fertile and infertile men. Patients and methods: Prospective case-control study comparing the findings of infertile men (n = 1168) to those of men with confirmed fertility (n = 100) regarding demographics and semen characteristics (conventional and advanced semen tests). Spearman rank correlation assessed the correlation between ORP, SDF, and different morphological indices. Means of ORP and SDF were assessed in variable levels of normal sperm morphology amongst all participants. Results: Infertile patients had a significantly lower mean sperm count (32.7 vs 58.7 × 10 6 sperm/mL), total motility (50.1% vs 60.4%), and normal morphology (5.7% vs 9.9%). Conversely, infertile patients had significantly higher mean head defects (54% vs 48%), and higher ORP and SDF values than fertile controls. ORP and SDF showed significant positive correlations and significant negative correlations with sperm head defects and normal morphology in infertile patients, respectively. ORP and SDF were significantly inversely associated with the level of normal sperm morphology. Using receiver operating characteristic curve analysis, ORP and SDF threshold values of 1.73 mV/10 6 sperm/mL and 25.5%, respectively, were associated with 76% and 56% sensitivity and 72% and 72.2% specificity, respectively, in differentiating <4% from ≥4% normal morphology. Conclusion: A direct inverse relationship exists between seminal ORP and SDF with various levels of normal sperm morphology. Using ORP and SDF measures in conjunction with standard semen morphology analysis could validate the result of the fertility status of patients. © 2017 Arab Association of UrologyScopu

Test Procedures for Advanced Characterization of Bituminous Binders Employed for Pavement Construction in Public Works Authority Road Projects - State of Qatar

This paper illustrates the approach adopted by the Public Works Authority (Ashghal) of the State of Qatar for the advanced chemical and rheological characterization of bituminous binders (both neat and modified). The ultimate objective of testing is to create a database of employed binders, which may be meaningful for the optimization of the selection of materials and for the consequent enhancement of pavement performance. This paper provides an illustration of employed testing procedure and briefly discusses typical experimental results

Use of Crumb Rubber Modified Binders and Asphalt Mixtures in Public Works Authority Road Projects - State of Qatar

This paper illustrates the approach adopted by the Public Works Authority (Ashghal) of the State of Qatar for the widespread implementation in road projects of paving technologies related to the use of crumb rubber modified binders (CRMBs). Such an approach has entailed the monitoring of a full-scale preliminary trial, the definition of a prequalification system for crumb rubber and CRMB producers, and the development of mix design and quality control guidelines applicable to CRMB asphalt mixtures. Experimental results obtained in the preparatory phases of work and during the approval process of materials and mixtures are critically presented

Endocrine contribution to the sexual dysfunction in patients with advanced chronic kidney disease and the role of hyperprolactinemia.

In this study, we investigated the prevalence of sexual dysfunction among males with advanced chronic kidney disease and the effect of treating hyperprolactinemia among these patients. In this prospective study, patients were assessed with history, physical examination, hormonal assessment, and two questionnaires, IIEF and AIPE. Patients with hyperprolactinemia received treatment with cabergoline 0.5 mg once per week for 6 months and were re-evaluated. A total of 102 patients were included in this study, 75 (73.53%) were on hemodialysis, 13 (12.75%) on peritoneal dialysis and 14 (13.73%) on medical treatment alone. Ninety (88.24%) patients had premature ejaculation, 85 (83.33%) had anything from mild-to-moderate-to-severe erectile dysfunction. The incidence of hypogonadism and hyperprolactinemia was 34.4%. Patients treated with cabergoline (n = 26) showed a significant increase in LH levels (p = .003) and a significant decrease in prolactin levels (p = .003). Testosterone levels and the incidence of erectile dysfunction or premature ejaculation did not improve significantly. There is a high incidence of sexual dysfunction among patients. Treatment of hyperprolactinemia is effective in correcting prolactin levels, but does not improve erectile dysfunction or premature ejaculation. Therefore, treating hyperprolactinemia is not an overall effective treatment for erectile dysfunction in these patients

Prevalence of HLA-B27 in Patients with Ankylosing Spondylitis in Qatar

Background and Objectives. The human leukocyte antigen HLA-B27 is a class 1 antigen of the major histocompatibility complex and is strongly associated with ankylosing spondylitis (AS). The purpose of the present study is to investigate the distribution of HLA-B27 in patients with AS of different ethnic groups in Qatar. Design and Setting. Study design was cross-sectional and the setting was rheumatology clinics of Hamad General Hospital in Qatar where most of ankylosing spondylitis patients are followed up. Patients and Methods. Patients with diagnosis of AS who met the New York modified criteria for AS were tested for HLA-B27. 119 patients were tested for HLA-B27: 66 Arabs, 52 Asians (Indians, Pakistanis, Bengalis, and Iranians), and one Western (Irish). Results. Of all the individuals, 82 were positive (69%) for HLA-B27. Among the Arabs, 49/66 were positive (74%). Among the Asians, 32/52 were positive (61%). Furthermore, Qatari patients (10 males and one female) 9 were positive (82%), 14/19 Jordanians/Palestinians were positive, and 9/10 (90%) Egyptians were positive. Among the Asians, 19/26 Indians were positive (73%), which was similar to the Arabs. Conclusion. HLA-B27 in our small group of Arabs is present in 74%. Comparison with other data will be presented in detail

Can AI help in screening Viral and COVID-19 pneumonia?

Coronavirus disease (COVID-19) is a pandemic disease, which has already caused thousands of causalities and infected several millions of people worldwide. Any technological tool enabling rapid screening of the COVID-19 infection with high accuracy can be crucially helpful to healthcare professionals. The main clinical tool currently in use for the diagnosis of COVID-19 is the Reverse transcription polymerase chain reaction (RT-PCR), which is expensive, less-sensitive and requires specialized medical personnel. X-ray imaging is an easily accessible tool that can be an excellent alternative in the COVID-19 diagnosis. This research was taken to investigate the utility of artificial intelligence (AI) in the rapid and accurate detection of COVID-19 from chest X-ray images. The aim of this paper is to propose a robust technique for automatic detection of COVID-19 pneumonia from digital chest X-ray images applying pre-trained deep-learning algorithms while maximizing the detection accuracy. A public database was created by the authors combining several public databases and also by collecting images from recently published articles. The database contains a mixture of 423 COVID-19, 1485 viral pneumonia, and 1579 normal chest X-ray images. Transfer learning technique was used with the help of image augmentation to train and validate several pre-trained deep Convolutional Neural Networks (CNNs). The networks were trained to classify two different schemes: i) normal and COVID-19 pneumonia; ii) normal, viral and COVID-19 pneumonia with and without image augmentation. The classification accuracy, precision, sensitivity, and specificity for both the schemes were 99.7%, 99.7%, 99.7% and 99.55% and 97.9%, 97.95%, 97.9%, and 98.8%, respectively.Comment: 12 pages, 9 Figure

M-SERVICE QUALITY OF TELECOMMUNICATION COMPANIES IN QATAR

Today, although mobile applications make our lives easier, the service quality provided by such applications has become a vital element in increasing customer satisfaction. This research paper aims to identify the significant mobile service quality factors (Application Design, Ease of Use, Information Content, Reliability, Responsiveness, Empathy, Security and Prices and offers) that influence customer satisfaction and loyalty in Qatar's telecommunications sector. To answer the research question and test the hypotheses that form the study model, data were collected through an online questionnaire of 195 random customers who use Ooredoo or Vodafone mobile applications in Qatar. The proposed model was evaluated using partial least squares structural equation modelling (PLS-SEM). The results show that Ease of Use, Information Content, Responsiveness and Security are the most significant factors that affect M-Customer Satisfaction. Also, there is a strong relationship between M-customer Satisfaction and M-loyalty. On the contrary, Application Design, Reliability, Empathy, and Prices and offers did not affect M-customer satisfaction. Thus, the managers in telecommunication companies should adopt a strategy that focuses on the M-service quality factors that most influence M-customer satisfaction to increase customer satisfaction rates and loyalty to their products and services. It will also help reduce overall costs by delivering those products and services to a higher proportion of customers through the mobile application rather than physical branches. This paper also helps the researchers use the proposed model in future research to understand these relationships in other countries better