Performance Enhancement of a Variable Speed Permanent Magnet Synchronous Generator Used for Renewable Energy Application

The paper aims to develop an improved control system to enhance the dynamics of a permanent magnet synchronous generator (PMSG) operating at varying speeds. The generator dynamics are evaluated based on lowing current, power, and torque ripples to validate the effectiveness of the proposed control system. The adopted controllers include the model predictive power control (MPPC), model predictive torque control (MPTC), and the designed predictive voltage control (PVC). MPPC seeks to regulate the active and reactive power, while MPTC regulates the torque and flux. MPPC and MPTC have several drawbacks, like high ripple, high load commutation, and using a weighting factor in their cost functions. The methodology of designed predictive voltage comes to eliminate these drawbacks by managing the direct voltage by utilizing the deadbeat and finite control set FCS principle, which uses a simple cost function without needing any weighting factor for equilibrium error issues. The results demonstrate several advantages of the proposed PVC technique, including faster dynamic response, simplified control structure, reduced ripples, lower current harmonics, and decreased computational requirements when compared to the MPPC and MPTC methods. Additionally, the study considers the integration of blade pitch angle and maximum power point tracking (MPPT) controls, which limit wind energy utilization when the generator speed exceeds its rated speed and maximize wind energy extraction during wind scarcity. In summary, the proposed PVC enhanced control system exhibits superior performance in terms of dynamic response, control simplicity, current quality, and computational efficiency when compared to alternative methods

Epidemiology of hepatitis viruses among hepatocellular carcinoma cases and healthy people in Egypt: A systematic review and meta-analysis

Liver cancers are strongly linked to hepatitis B virus (HBV) and hepatitis C virus (HCV). Egypt has the highest prevalence of HCV worldwide and has rising rates of hepatocellular carcinoma (HCC). Egypt's unique nature of liver disease presents questions regarding the distribution of HBV and HCV in the etiology of HCC. Accordingly, a systematic search of MEDLINE, ISI Web of Science, ScienceDirect and World Health Organisation databases was undertaken for relevant articles regarding HBV and HCV prevalence in Egypt among healthy populations and HCC cases. We calculated weighted mean prevalences for HBV and HCV among the populations of interest and examined differences in prevalence by descriptive features, including age, year and geographic region. Prevalences for HBV and HCV were 6.7% and 13.9% among healthy populations, and 25.9% and 78.5% among HCC cases. Adults had higher prevalences of both infections (Adult HBV = 8.0%, Child HBV = 1.6%; Adult HCV = 15.7%, Child HCV = 4.0%). Geographically, HBV was higher in the south, whereas HCV was greater in the north (North HBV = 4.6%, South HBV = 11.7%; North HCV = 15.8%, South HCV = 6.7%). Among HCC cases, HBV significantly decreased over time ( p = 0.001) while HCV did not, suggesting a shift in the relative influences of these viruses in HCC etiology in Egypt. Our results highlight large amounts of heterogeneity among the epidemiological factors associated with liver disease in Egypt and underscore the necessity of an integrated strategy for the successful prevention of viral hepatitis infections and chronic liver disease. © 2008 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/61320/1/23937_ftp.pd

Optimal Decentralized LQR Control to Enhance Multi-Area LFC System Stability

Many studies have been made in the field of load frequency control (LFC) through the last few decades because of its importance to healthy power system. It is important to maintain frequency deviation at zero level after a load perturbation. In decentralized control, the multi-area power system is decomposed into many single input single output (SISO) subsystems and a local controller is designed for each subsystem. The controlled subsystems may have slow poles; these undesired poles may drive the aggregated overall system into the instability region. Thus, it is required to relocate these poles to much more stable places to avoid their effect upon the overall system stability. This study aims to design a new load frequency controller based on the powerful optimal linear quadratic regulator (LQR) technique. This technique can be applied over subsystem level to shift each subsystem undesired poles one by one into a prespecified stable location which in turn shift the overall system slow poles and reduce the effect of the interaction between the interconnected subsystems among each other. This procedure must be applied many times as the number of undesired poles (pairs) until all the desired poles are achieved. The main objective is considered to get a robust design when the system is affected by a physical disturbance and ±40% model uncertainties. LQR can be applied again over the aggregated system to enhance the stability degree. Simulation results are used to evaluate the effectiveness of the proposed method and compared to other research results

Synthesis, Cytotoxic Activity, Crystal Structure, DFT Studies and Molecular Docking of 3-Amino-1-(2,5-dichlorophenyl)-8-methoxy-1<i>H</i>-benzo[<i>f</i>]chromene-2-carbonitrile

The target compound 3-amino-1-(2,5-d ichlorophenyl)-8-methoxy-1H-benzo[f]-chromene-2-carbonitrile (4) was synthesized via a reaction of 6-methoxynaphthalen-2-ol (1), 2,5-dichlorobenzaldehyde (2), and malononitrile (3) in ethanolic piperidine solution under microwave irradiation. The newly synthesized β-enaminonitrile was characterized by FT-IR, 1H NMR, 13C NMR, mass spectroscopy, elemental analysis and X-ray diffraction data. Its cytotoxic activity was evaluated against three different human cancer cell lines MDA-MB-231, A549, and MIA PaCa-2 in comparison to the positive controls etoposide and camptothecin employing the XTT cell viability assay. The analysis of the Hirshfeld surface was utilized to visualize the reliability of the crystal package. The obtained results confirmed that the tested molecule revealed promising cytotoxic activities against the three cancer cell lines. Furthermore, theoretical calculations (DFT) were carried out with the Becke3-Lee-Yang-parr (B3LYP) level using 6-311++G(d,p) basis. The optimization geometry for molecular structures was in agreement with the X-ray structure data. The HOMO-LUMO energy gap of the studied system was discussed. The intermolecular-interactions were studied through analysis of the topological-electron-density(r) using the QTAIM and NCI methods. The novel compound exhibited favorable ADMET properties and its molecular modeling analysis showed strong interaction with DNA methyltransferase 1

Egyptian evidence-based consensus on clinical practice recommendations for the management of systemic sclerosis

Abstract Background This work aims to develop clinical practice recommendations for the management of systemic sclerosis (SSc). Results Fourteen expert panels had completed the two rounds of surveys. After the end of round 2, recommendations were released and distributed on 11 domains. The percentage of the agreement on the recommendations was 92.3% to 100%. All 11 key questions were answered at the end of the second round with agreement. Conclusion This guideline tried to tackle the gaps in research that limit treatment options. Stratifying the patients according to their disease domains has helped to set up sequential management pathways for each domain

Development of practice guidelines for hemodialysis in Egypt

Although hemodialysis is the main modaility of treatment of end-stage renal disease, no practice guidelines are available in Egypt. Applying international guidelines for hemodialysis would not be suitable or feasible, because of different health system and lack of resources. The aim of this project was the development of evidence- and consensus-based clinical practice guidelines for hemodialysis in Egypt. The Egyptian guidelines were adopted from the standards developed by The College of Physicians and Surgeons of Alberta (Canada), The National Kidney Foundation (USA), The Clinical Standards Board for Scotland (Scotland), and The College of Physicians and Surgeons of Ontario (Canada). In addition, the guidelines published in Oxford Handbook of Dialysis were reviewed. Thereafter, a panel of Egyptian experts in the field of nephrology and hemodialysis was selected and invited to participate in this project. The Delphi technique was applied to build up the consensus among the experts on the formulated guidelines. The final version of the Egyptian Hemodialysis Practice Guidelines included five main sections; personnel, patient care practices, infection prevention and control, facility, and documentation/records. A consensus on practice guidelines for hemodialysis has been successfully produced and is supported by levels of evidence. The 12 Egyptian experts who participated in the Delphi technique and the reviewers assured the completeness and acceptability of the developed practice guidelines. Also, including experts from the university hospitals together with the Directorates of Cairo and Giza Health Affairs of the Egyptian Ministry of Health (MOH) avoided conflicts between clinical recommendations and feasible application in the MOH hemodialysis facilities

The clinical musculoskeletal ultrasonography: Egyptian guidelines for structured musculoskeletal ultrasound scanning and reporting

Abstract Background The aim of this work is to set up the standards for performing musculoskeletal ultrasound scans and reporting as an additional procedure in the rheumatology setting. We used two rounds of the Delphi approach to get the consensus on a musculoskeletal ultrasound reporting. Results Fifteen expert panels had completed the two rounds of surveys. After the end of round two, eighteen recommendations distributed upon eight domains were released. The percentage of the agreement on the recommendations was 93.3 to 100 %. All eighteen key questions were answered at the end of the second round with agreement. Conclusion A musculoskeletal ultrasound report template has been developed by this study, based on outcomes of a Delphi process, by an international participants’ panel. All domains met the 80% voting threshold set in this work. The reporting template can be used for both clinical research as well as standard practice to provide guidance and standardize the musculoskeletal ultrasound reporting