Voltage and Reactive Power Control in Islanded Microgrids

Previous studies put on view lots of advantages and concerns for islanded microgrids (IMGs), whether it is initiated for emergency, intentionally planned or permanent island system purposes. From the concerns that have not been addressed yet, such as: 1) The ability of the distributed generation (DG) units to maintain equal reactive power sharing in a distribution system; 2) The ability of the DG units to maintain acceptable voltage boundary in the entire IMG; 3) The functionality of the existing voltage and reactive power (Volt/Var) DG, this thesis analyzes the complexity of voltage regulations in droop-controlled IMGs. A new multi-agent algorithm is proposed to satisfy the reactive power sharing and the voltage regulation requirements of IMGs. Also, the operation conflicts between DG units and Volt/Var controllers, such as shunt capacitors (SCs) and load-ratio control transformer (LRT) during the IMG mode of operation, are investigated in this thesis. Further, a new local control scheme for SCs and LRTs has been proposed to mitigate their operational challenges in IMGs

Effect of a combined machining/burnishing tool on the roughness and mechanical properties

Burnishing is a cold working surface treatment process in which plastic deformation of surface irregularities occurs by exerting pressure through a very hard and a very smooth roller or ball on a surface to generate a uniform and work-hardened surface. This treatment occurs generally after the machining process. In this study, a new combined machining/burnishing tool is designed and is fabricated. This tool allows for generating simultaneously the machining (turning) and the burnishing of the cylindrical surface using a turning machine. First, turned surfaces at different conditions, sketches, finishing and half finishing were performed using only the cutting tool. The evolutions of a surface roughness parameter and the technological time relative to every test condition have been investigated. Second, using the combined machining/burnishing tool at coarse conditions, the evolutions of the surface roughness and the technological time have been also investigated. A comparison among the parameters obtained under different machining conditions and those obtained using the combined machining/burnishing tool has been carried out. Moreover, the analyses of the layers obtained on the combined machined/burnished surface have shown that the burnishing process induces compressive residual stresses on the subsurface treated specimens

FOXO3a gene polymorphism and bronchial asthma in Egyptian children INTRODUCTION Bronchial asthma is the most prevalent chronic immunological disorder in childhood period. It is characterized by airways inflammation and bronchial hyper-responsiveness where

Background: FOXO3a proteins play multiple crucial roles in immune response. FOXO3 inhibits T cell proliferation, induces T cell apoptosis via upregulation of proapoptotic proteins and it suppresses T cell activation preventing autoimmunity. The role of FOXO3a gene in the pathogenesis of bronchial asthma has been studied in few ethnic groups and revealed its implication in asthma pathogenesis.Objectives: The aim of the current study is to detect the association between single nucleotide polymorphism of the FOXO3a gene (rs13217795) and bronchial asthma, atopy and asthma severity in Egyptian children.Methods: The current cross-sectional case-control study was performed on 75 asthmatic children aged 2 to 12 years following up in the pulmonology outpatient clinic in Children's hospital, Cairo University and 75 age and sex matched healthy controls. Candidates were subjected to clinical evaluation in addition to genotyping for the FOXO3a gene polymorphism using PCR-RFLP technique.Results: The highest frequency was for the heterozygous type CT in both cases and controls groups. The genotype frequencies of mutant type TT for cases and controls were 12 % and 16% respectively, and the T allele frequencies were 37.2% in cases and 46.7% in the control group while CC genotype was present in 37.3% of asthmatic patients and 22.6% in the controls and the C allele was detected in 62.8% and 53.3% for cases and controls respectively. No statistically significant differences were observed between asthmatic patients and controls regarding the different genotypes of the FOXO3a gene polymorphism (p=0.161). No significant association was detected between the different genotypes of the FOXO3a gene polymorphism and the atopic status (p=0.536) or the different grades of asthma severity (p= 0.545).Conclusions: The study of FOXO3a gene polymorphism (rs13217795) in asthmatic Egyptian children revealed low frequency of the mutant TT genotype among cases and controls. In the current study, FOXO3a polymorphism has no role in the pathogenesis of asthma or atopy. Moreover, it has no relation to degree of disease severity.Keywords: Asthma, FOXO3a, gene, children, Egyptian, polymorphis

The WTO dispute settlement understanding : how can Africa make better use of the system? using Egypt as a case study

The Dispute Settlement Understanding (DSU) established under the World Trade Organisation, is one of the most notable achievements of the multilateral trading system. African countries need to engage more in this emerging system to defend their trade and economic interests, especially in this time of increasing integration in the world trading system. It is submitted that the weak participation of African countries in the DSU can have negative economic and trade implications on Africa, as it minimises the influence these countries could exert on the development of the DSU legal system at this stage of particular importance to the evolution of international trade law in addition to its direct economic and trade costs. All complaints about impediments in the DSU cannot be rightly claimed to be the core reasons for weak African participation in the system, as the system still stand out as a rule-based with equal treatment to Developed and Developing countries. Additionally, the low participation of African countries cannot be justified by the degree of development basis only, as other developing counties have been very successful in this regard and some African countries managed to make use of the system in a very positive way. Moreover, this dissertation states that the effect of other internal constraints that are reported to hinder African participation, such as lack of sufficient financial resources, limited technical expertise and political factors, could be minimised through joint African cooperation, and by developing national strategies to deal with DSU. Egypt is a good example in this regard; despite its limited financial and technical expertise, it managed to gain accumulated experience through its various forms of engaging in the DSU, and consequently managed to defend its trade and economic interests. The establishment of a national organisational framework to deal with the DSU assisted in the preparation of national expertise that is gaining increasing experience. Egypt’s incorporation of national legislations on Anti-Dumping, Investment Protection, Intellectual Property Rights and other WTO agreements definitely supports the Egyptian position in the DSU. African countries are called to work within the African Union and on the national levels to make the best use of the system to serve their developmental goals. National strategies should be formulated regarding WTO dispute settlement engagement. These should include sound legislations and clear rules of engagement between different departments and the private sector to enable African countries to overcome the major constraints currently limiting their participation. African countries can depend partially on the support system offered by organisations like ACWL, UNCTAD and pro bone assistance from international law firms and NGO’s to overcome the financial and lack of experience constraints.Dissertation (LLM)--University of Pretoria, 2010.Public Lawunrestricte

Frequency of neurological manifestations in β-thalassaemic patients in Zagazig University Hospitals

Background: Beta thalassemia syndrome is a hereditary disorder characterized by reduced or absent synthesis of thebeta chains of hemoglobin that disturbs the normal shape of red blood cells. Chronic hypoxia of the nerves resulting from severe anemia may contribute to the pathogenesis of the peripheral neuropathy in patients with β-thalassemia. The aim of this study was to find out the frequency of neurological manifestations in β- thalassemia patients and to determine the contributing factors that lead to these manifestations.Patients and Methods: This study was prospective cross sectional study conducted during the period from June 2019 to December 2020. This study was carried out on 120 thalassemia patients (67 males and 53 females), with ages ranged from 11 to 22 years old with a mean age of 16.45+3.31 years.Results: About 31.7% of the studied cases had neurological manifestations. Tingling and numbness were the main neurological symptoms among cases (24.1% and 23.3% respectively) followed by headache (21.7%), joint and muscle pain (20.8%) and tremors in hands (3.3%). Hypotonia was found in 25 cases (20.8%). Grade 4 muscle power was reported in 13 cases (10.8%) and normal (grade 5) muscle power was reported in 107 cases (89.1%). Deep tendon reflexes were normal in (89.2%) cases, while (10.8%) cases had brisk deep tendon reflexes.Conclusion: Frequency of neurological manifestations in beta thalassemia patients was 31.7%. About 26.3% of them had abnormal nerve conduction study (NCS). Age >16 years old, short stature, prolonged duration of the disease, transfusion frequency >10 times/year, delayed puberty and jaundice were risk factors for neurological manifestations in our studied cases

Synthesis and biological assessment of new benzothiazolopyridine and benzothiazolyl- triazole derivatives as antioxidant and antibacterial agents

ABSTRACT. A novel series of benzothiazolopyridine derivatives was synthesized via interaction of -2-(benzothiazol-2-yl)-3-(4-chlorophenyl)acrylonitrile (2) with a diverse of commercially available reagents (indandione, thiobarbituric acid, and malononitrile). Moreover, a novel group of benzothiazole linked substituted 1,2,3-triazole derivatives were synthesized by exploring the chemical behavior of 5-benzothiazolyl-2-(4-chlorophenyl)-triazol-4-amine through refluxing in glacial acetic acid, condensation with phthalic anhydride, and cyanoacetylation reactions. All newly synthetized compounds have been tested for their antioxidant and antibacterial activities compared with ascorbic acid and Ampicillin as reference drugs, respectively. The benzothiazolo- pyridopyrimidine compound 6 was found the most potent antioxidant agent with IC50 = 0.015 mg/mL compared to the results of ascorbic acid (IC50 = 0.022 mg/mL). The investigated compounds showed no antibacterial properties against Gram-negative bacterial species, Pseudomonas aeruginosa and Escherichia coli. Benzothiazolopyridine derivative 5 displayed the best growth inhibition against Gram-positive bacteria, Staphylococcus aureus and Bacillus cereus with inhibition zones 24 and 20 mm, respectively.   KEY WORDS: Benzothiazole, Pyridobenzothiazole, 1,2,3-Triazole, Naphtharidine, Antioxidant   Bull. Chem. Soc. Ethiop. 2022, 36(2), 451-463.                                                              DOI: https://dx.doi.org/10.4314/bcse.v36i2.17                                                     &nbsp

Defying role of specific microorganisms on efficiency of organic materials (olive pomace) on the growth and productivity of olive trees

This study has been carried out through three successive seasons (2012, 2013 and 2014) on 12 years old Manzanillo olive trees in a private orchard located at 50 km of Cairo – Alexandria road in north-west of Egypt. The main objective of this study was to improve the physical and chemical properties of olive pomace by adding microorganisms specific to phenolic substances, which leads to their disposal and suitability for cultivation. Two microorganisms (Trichoderma virdi and Pseudomonas fluorescens) were evaluated to determine their promoting effect on the growth and productivity of olive trees. The experiment consisted of 9 treatments, 2 trees per treatment replicated 3 times in a randomized block design. Data exerted that, the treatment with compost 50 % + Pomace 50 % + Pseudomonas fluorescens gave the highest fruit set (%), yield, remaining fruits and leaf nitrogen and potassium. While, using the compost 75% + pomace 25 % + Trichoderma virdi + Pseudomonas fluorescens recorded the highest number of leaves and inflorescence/meter.Conclusively, it could be recommended under the same conditions of this study, using pomace (olive mill wastes) at the rate of compost (Comp.) 50 % + Pomce (Pom.) 50 % + Pseudomonas fluorescens (Pseu.) to increase the productivity of Manzanillo olive trees

بناء نموذج انحدار متعدد لاستهلاك الكهرباء في قطاع غزة

This paper aims to build multiple regression model to identify the significant variables which affect the electricity consumption for households in Gaza Strip. This can be achieved through the study of the current situation and the obstacles facing the electricity consumption in Gaza Strip, which has a high privacy that differs from all the countries in the world. The Problem of electricity increases as the gap between supply and demand increases over time and resulting on significant impact on different aspects of life. The household represents the largest proportion in electricity consumption and number of subscribers in Gaza Strip. The method of Generalized Least Squares (GLS) is used to build the electricity consumption model. This model indicates that the most significant independent variables are: No commitment to pay electricity bills, the average of per capita income, and average per subscription share of electricity for the households. The result shows that 99.3% of the variability of electricity consumption is explained by these variables. One of the main recommendations of this research: provide a separate subscription for each apartment, the obligation for paying the monthly electricity bills, compromise of arrears, as well as the rationalizing use of electricity.يهدف البحث إلى بناء نموذج انحدار متعدد ليحدد المتغيرات المؤثرة على استهلاك الكهرباء للقطاع العائلي في قطاع غزة، وذلك من خلال دراسة الواقع الحالي والمعيقات التي تواجه استهلاك الكهرباء في قطاع غزة، والتي تتمتع بخصوصية تختلف عن جميع البلدان في العالم. تزداد مشكلة الكهرباء باتساع الفجوة بين العرض والطلب وتتزايد مع مرور الوقت محدثة أثراً كبيراً في نواحي الحياة المختلفة. يمثل القطاع العائلي النسبة الأكبر في الاستهلاك وفي عدد المشتركين في قطاع غزة. تم استخدام طريقة المربعات الصغرى المعممة في بناء نموذج استهلاك الكهرباء. تبين من خلال النموذج أن أهم المتغيرات المستقلة المؤثرة على الاستهلاك هي: عدم الالتزام بدفع فواتير الكهرباء، متوسط دخل الفرد، ومتوسط نصيب الاشتراك الواحد من الكهرباء للقطاع العائلي. تبين أن هذه المتغيرات قد ساهمت في تفسير 99.3% من التغير الكلي في استهلاك الكهرباء للقطاع العائلي في قطاع غزة. ومن أهم توصيات هذا البحث توفير اشتراك مستقل لكل شقة سكنية، الالتزام بدفع قيمة الخدمات الشهرية من الكهرباء، تسوية المتأخرات، وكذلك ترشيد استخدام الكهرباء. الكلمات الافتتاحية: الانحدار المتعدد؛ طريقة المربعات الصغرى المعممة؛ الارتباط الذاتي؛ التداخل الخطي المتعدد؛ ثبات التباين؛ استهلاك الكهرباء

GLOBAL METHYLATION PATTERN CHANGES IN BREAST AND COLORECTAL CANCER CELLS TREATED WITH DIFFERENT CHEMOTHERAPEUTIC DRUGS

Cancer in a global threat as it is considered the primary cause of death worldwide. Breast cancer is the most common cancer I female worldwide. In the present study we evaluated the role of temozolomide, carboplatin, sodium phenylbutyrate, and cyclophosphamide in changing the methylation landscape of four tumor cell liness; breast, colorectal, lung, and cervical. Cells were treated with 5 µM of each drug and the cells were incubated with the drugs for 48 and 96 h before reading the changes in methylation patterns. Global methylation quantification was measured in cells after being treated with the drugs. Data obtained indicated that sodium phenylbutyrate, followed by temozolomide were the drugs most efficient in hypermethylation of the DNA, while carboplatin followed by cyclophosphamide were able to reduce the concentration of 5-mC in the DNA. It has been concluded that using carboplatin in combination with sodium phenylbutyrate (PBA) might induce cell cycle arrest of malignant cells. Further studies are needed to highlight the mechanism of action of these drugs when combined in treatment of cancer. Keywords: methylation; breast; colon; lung; cervical; epigenetics