Power quality issues of 3MW direct-driven PMSG wind turbine

This paper presents power quality issues of a grid connected wind generation system with a MW-class direct-driven permanent magnet synchronous generator (PMSG). A variable speed wind turbine model was simulated and developed with the simulation tool of PSCAD/EMTDC. The model includes a wind turbine with one mass-model drive train model, a PMSG model and a full-scale voltage source back to back PWM converter. The converter controller model is employed in the dq-synchronous rotating reference frame and applied to both generator and grid sides. To achieve maximum power point tracking, a tip speed ratio method is applied in machine side, whereas DC voltage control is applied in grid side to achieve constant DC voltage. Due to wind fluctuation and power oscillation as a result of wind shear and tower shadow effects (3p), there will be a fluctuation in the output power and voltage. The concerned power quality issues in this work are Harmonics, power fluctuation and flicker emission. The measurements will be carried out under different wind speed and circumstances

Comparative power quality study of variable speed wind turbines

Due to the variabilities inherent to natural wind resources and the associated electronic power present, wind power produces fluctuations in the generated power and harmonic injection entering the electric grid. This paper compares power quality issues and the impact on the power system of wind reliant power systems when using two different types of variable speed wind generators: the direct-drive permanent-magnet synchronous generator, and the doubly-fed induction generator. First, it gives an overview of the system structure of each generator, and then both systems are simulated to determine their behavior and the consequent impact on power quality. The power quality aspects addressed are voltage fluctuation (Flicker), current harmonics, response to voltage dip, and voltage stability. After this assessment, the contribution of both generators to severe three-phase faults was tested and then, finally, fault-ride through

Knowledge Management in the Pharmaceutical Industry: Between Academic Research and Industry Regulations

The pharmaceutical sector is one of the pillars of the world’s economy. A significant proportion of its value lies in intellectual assets generated through continuous innovation and lengthy development cycles within a strictly regulated environment. The purpose of this paper is to address the gap between knowledge management (KM) as an expanding academic discipline in the pharmaceutical industry and at the same time a growing regulatory expectation. A systematic review of 137 refereed KM articles revealed six empirical research themes in the pharmaceutical industry. In a subsequent step, the discovered themes and subthemes were compared with the extant regulatory expectations as explained in 128 regulatory guidelines. Findings shed the light on the gap between academic KM research and the current thinking of regulatory bodies. Some regulated knowledge processes were underrepresented in academic literature. The paper offers also novel insights and recommendations for future developments in academic research, regulations and/or industry

Neoadjuvant chemotherapy versus primary surgery in advanced ovarian carcinoma

BACKGROUND: Patients with advanced ovarian cancer should be treated by radical debulking surgery aiming at complete tumor resection. Unfortunately about 70% of the patients present with advanced disease, when optimal debulking can not be obtained, and therefore these patients gain little benefit from surgery. Neoadjuvant chemotherapy (NACT) has been proposed as a novel therapeutic approach in such cases. In this study, we report our results with primary surgery or neoadjuvant chemotherapy as treatment modalities in the specific indication of operable patients with advanced ovarian carcinoma (no medical contraindication to debulking surgery). PATIENTS AND METHODS: A total of 59 patients with stage III or IV epithelial ovarian carcinomas were evaluated between 1998 and 2003. All patients were submitted to surgical exploration aiming to evaluate tumor resectability. Neoadjuvant chemotherapy was given (in 27 patients) where optimal cytoreduction was not feasible. Conversely primary debulking surgery was performed when we considered that optimal cytoreduction could be achieved by the standard surgery (32 patients). RESULTS: Optimal cytoreduction was higher in the NACT group (72.2%) than the conventional group (62.4%), though not statistically significant (P = 0.5). More important was the finding that parameters of surgical aggressiveness (blood loss rates, ICU stay and total hospital stay) were significantly lower in NACT group than the conventional group. The median overall survival time was 28 months in the conventional group and 25 months in NACT group with a P value of 0.5. The median disease free survival was 19 months in the conventional group and 21 months in NACT group (P = 0.4). In multivariate analysis, the pathologic type and degree of debulking were found to affect the disease free survival significantly. Overall survival was not affected by any of the study parameters. CONCLUSION: Primary chemotherapy followed by interval debulking surgery in select group of patients doesn't appear to worsen the prognosis, but it permits a less aggressive surgery to be performed

A Scientometric Analysis of Knowledge Management Research and Practice Literature: 2003 – 2015

The purpose of this paper is to explore the current research trends in Knowledge Management (KM) through a scientometric analysis of all literature published in KMRP between 2003 and 2015 (506 articles). The review framework explores three sets of review questions addressing Research Productivity, Research Themes and Methods, and Citation Analysis. The study elucidates wide global interest in KM and an increasing trend towards multi-author collaboration. Although more than 55 different industries have featured in the journal, certain knowledge-intensive sectors remain underrepresented. Country productivity shows few nations taking the lead with an interesting correlation between research activity and economic prosperity. Moreover, a growing tendency towards empirical methods is observed in contrast to a decrease in literature review papers, coupled with a recent rise in articles that integrate KM and Information Technology (IT). In terms of citation and influences, few published articles have stood out in the journal’s history. This is the first comprehensive scientometric research of KMRP describes the state-of-the-art value and provides an outlook of the future

A framework for automatic semantic video annotation

The rapidly increasing quantity of publicly available videos has driven research into developing automatic tools for indexing, rating, searching and retrieval. Textual semantic representations, such as tagging, labelling and annotation, are often important factors in the process of indexing any video, because of their user-friendly way of representing the semantics appropriate for search and retrieval. Ideally, this annotation should be inspired by the human cognitive way of perceiving and of describing videos. The difference between the low-level visual contents and the corresponding human perception is referred to as the ‘semantic gap’. Tackling this gap is even harder in the case of unconstrained videos, mainly due to the lack of any previous information about the analyzed video on the one hand, and the huge amount of generic knowledge required on the other. This paper introduces a framework for the Automatic Semantic Annotation of unconstrained videos. The proposed framework utilizes two non-domain-specific layers: low-level visual similarity matching, and an annotation analysis that employs commonsense knowledgebases. Commonsense ontology is created by incorporating multiple-structured semantic relationships. Experiments and black-box tests are carried out on standard video databases for action recognition and video information retrieval. White-box tests examine the performance of the individual intermediate layers of the framework, and the evaluation of the results and the statistical analysis show that integrating visual similarity matching with commonsense semantic relationships provides an effective approach to automated video annotation

Out-of-Wedlock Pregnancy Among Single Mothers in Khartoum, Sudan: Sociodemographic Characteristics, Causes, and Consequences

Background: Out-of-wedlock childbearing is a global phenomenon that has lifelong consequences on the lives of both mothers and their children. The aim of this study is to identify the sociodemographic characteristics, causes, and consequences of outof- wedlock pregnancy among single mothers in Khartoum, Sudan.Methods: This descriptive, cross-sectional study was conducted at the Mygoma Orphanage Center (MOC) and Shamaa Rehabilitation Center (SRC) using convenience sampling among 200 participants. A validated questionnaire with 25 items was used to collect data. The data were entered into Epi-Data Manager and analyzed using the SPSS. Results: The study found that most of the single mothers in Khartoum who gave birth out of wedlock were young and had just completed their university education. Most of them discovered their pregnancy during the second or third trimester, and nearly half of them did not receive any antenatal care. The majority of the children born to these mothers were preterm and had a low birth weight. Additionally, many mothers reported experiencing social stigma and rejection from their families due to their out-of-wedlock pregnancy. The study also highlighted loneliness, stress, and romantic relations as the main causes of out-of-wedlock pregnancy among single mothers in Khartoum, Sudan.Conclusion: The study provides useful insights into the sociodemographic characteristics, causes, and consequences of out-of-wedlock pregnancy among single mothers in Khartoum, Sudan. Social stigma and lack of support were identified as significant barriers to the reintegration of single mothers and their children into society. Future research should focus on investigating the long-term effects of outof- wedlock pregnancy on mothers and their children

Clinical impact and diagnostic accuracy of 2-[18F]-fluoro-2-deoxy-d-glucose positron-emission tomography/computed tomography (PET/CT) brain imaging in patients with cognitive impairment: a tertiary centre experience in the UK

Aim To evaluate the clinical impact of combined 2-[18F]-fluoro-2-deoxy-D-glucose (FDG) positron-emission tomography/computed tomography (PET/CT) brain imaging performed in selected patients with cognitive impairment at a tertiary referral centre in the UK, and to assess the accuracy of FDG PET/CT to correctly establish the diagnosis of Alzheimer's dementia (AD) in “real-world” clinical practice. Methods and materials Using an institutional radiology database, 136 patients were identified for inclusion in the study. FDG PET/CT was performed using a standard technique and interpreted by dual-trained radiologists and nuclear medicine physicians. Standardised questionnaires were sent to the referring clinicians to establish the final clinical diagnosis and to obtain information about the clinical impact of FDG PET/CT. Results There was a 72% questionnaire return (98/136), with mean patient follow-up of 471 (standard deviation 205) days. FDG PET/CT had an impact on patient management in 81%, adding confidence to the pre-test diagnosis in 43%, changing the pre-test diagnosis in 35%, reducing the need for further investigations in 42%, and resulting in a change in therapy in 32%. There was substantial correlation between the PET/CT diagnosis and final clinical diagnosis with a correlation (k) coefficient of 0.78 (p<0.0001). The accuracy of FDG PET/CT in diagnosis of AD was 94% (95% confidence interval [CI]: 87–99), with a sensitivity of 87% (95% CI: 75–92) and a specificity of 97% (95% CI: 87–99). Conclusion FDG PET/CT brain imaging has a significant clinical impact when performed selectively in patients with cognitive impairment and shows high accuracy in the diagnosis of AD in “real-world” clinical practice

Cracking in asphalt materials

This chapter provides a comprehensive review of both laboratory characterization and modelling of bulk material fracture in asphalt mixtures. For the purpose of organization, this chapter is divided into a section on laboratory tests and a section on models. The laboratory characterization section is further subdivided on the basis of predominant loading conditions (monotonic vs. cyclic). The section on constitutive models is subdivided into two sections, the first one containing fracture mechanics based models for crack initiation and propagation that do not include material degradation due to cyclic loading conditions. The second section discusses phenomenological models that have been developed for crack growth through the use of dissipated energy and damage accumulation concepts. These latter models have the capability to simulate degradation of material capacity upon exceeding a threshold number of loading cycles.Peer ReviewedPostprint (author's final draft

Reliability evaluation of Lithium-Ion batteries for e-mobility applications from practical and technical perspectives: A case study

Copyright: © 2021 by the authors. Evaluation of the reliability of the components of electric vehicles (EVs) has been studied by international research centers, industry, and original equipment manufacturers over the last few years. Li-ion batteries are the main sensitive component of an EV’s E-power train. In other words, the Li-ion batteries for electromobility applications are one of the main components of an EV, which should be reliable and safe over the operational lifetime of the EV. Thus, investigating how to assess the reliability of the Li-ion battery has been a highly recommended task in most European projects. Moreover, with the increase in the number of new EVs made by European car companies, there has been a competition for market acquisition by these companies to win over customers and gain more market share. This article presents a comprehensive overview of the evaluation of the reliability of Li-ion batteries from practical and technical perspectives. Moreover, a case study for assessing reliability from practical and technical perspectives has been investigated.Deanship of Scientific Research at Jouf University, Saudi Arabia (Grant No. DSR-2021-02-0309)