Optimal frequency control in microgrid system using fractional order PID controller using Krill Herd algorithm

This paper investigates the use of fractional order Proportional, Integral and Derivative (FOPID) controllers for the frequency and power regulation in a microgrid power system. The proposed microgrid system composes of renewable energy resources such as solar and wind generators, diesel engine generators as a secondary source to support the principle generators, and along with different energy storage devices like fuel cell, battery and flywheel. Due to the intermittent nature of integrated renewable energy like wind turbine and photovoltaic generators, which depend on the weather conditions and climate change this affects the microgrid stability by considered fluctuation in frequency and power deviations which can be improved using the selected controller. The fractional-order controller has five parameters in comparison with the classical PID controller, and that makes it more flexible and robust against the microgrid perturbation. The Fractional Order PID controller parameters are optimized using a new optimization technique called Krill Herd which selected as a suitable optimization method in comparison with other techniques like Particle Swarm Optimization. The results show better performance of this system using the fractional order PID controller-based Krill Herd algorithm by eliminates the fluctuations in frequency and power deviation in comparison with the classical PID controller. The obtained results are compared with the fractional order PID controller optimized using Particle Swarm Optimization. The proposed system is simulated under nominal conditions and using the disconnecting of storage devices like battery and Flywheel system in order to test the robustness of the proposed methods and the obtained results are compared.У статті досліджено використання регуляторів пропорційного, інтегрального та похідного дробового порядку (FOPID) для регулювання частоти та потужності в електромережі. Запропонована мікромережева система складається з поновлюваних джерел енергії, таких як сонячні та вітрогенератори, дизельних генераторів як вторинного джерела для підтримки основних генераторів, а також з різних пристроїв для накопичування енергії, таких як паливна батарея, акумулятор і маховик. Через переривчасту природу інтегрованої відновлювальної енергії, наприклад, вітрогенераторів та фотоелектричних генераторів, які залежать від погодних умов та зміни клімату, це впливає на стабільність мікромережі, враховуючи коливання частоти та відхилення потужності, які можна поліпшити за допомогою вибраного контролера. Контролер дробового порядку має п’ять параметрів порівняно з класичним PID-контролером, що робить його більш гнучким та надійним щодо збурень мікромережі. Параметри PID-контролера дробового порядку оптимізовані за допомогою нової методики оптимізації під назвою «зграя криля», яка обрана як підходящий метод оптимізації порівняно з іншими методами, такими як оптимізація методом рою частинок. Результати показують кращі показники роботи цієї системи за допомогою алгоритму «зграя криля», заснованого на PID-контролері дробового порядку, виключаючи коливання частоти та відхилення потужності порівняно з класичним PID-контролером. Отримані результати порівнюються з PID-контролером дробового порядку, оптимізованим за допомогою оптимізації методом рою частинок. Запропонована система моделюється в номінальному режимі роботи та використовує відключення накопичувальних пристроїв, таких як акумулятор та маховик, щоб перевірити надійність запропонованих методів та порівняти отримані результати

Towards a textual theory of metonymy: a semiotic approach to the nature and role of metonymy in text

This thesis argues that the scope of metonymy throughout history remains severely reduced to a process of word substitution and the signifying potential of the trope is limited to lexical representation. The study therefore proposes a semiotic approach to take the trope beyond this limitation and to develop a textual theory to the trope. A background study related to how metonymy is treated in previous studies is therefore necessary. This review of literature covers a long period starting from ancient Greece and going up to the present day. Chapters one and two of this thesis, which give this general background, show that the hypothesis is to a large extent valid. The thesis then examines another related hypothesis which is that metonymy is semiotic in nature and a semiotic approach to metonymy will solve the problem of reductionism in the treatment of this trope. Chapter three is devoted to an examination of this hypothesis. It shows that a semiotic approach to metonymy is not only possible but also crucial. The semiotic approach to metonymy basically concerns the treatment of metonymy as a sign which cuts across three domains of representation. These are the domain of words, the domain of concepts and the domain of things or objects. The last domain is itself treated from a semiotic perspective to stand for the domain of context at large. on the basis of this semiotic approach to metonymy a textual model of metonymic relations in text is constructed. this model is put to the test in chapter four. here the metonymic relations of form for form, form for concept, form for thing, thing for form and concept for form are brought to bear on the formal and semantic connectedness of text. in chapter five the metonymic relations of concept for concept, concept for thing, thing for thing and thing for concept are used to explain how these metonymic relations interact to provide a linkage between language, cognition and context

Managing Stakeholder Conflicting Expectations in Higher Education: a Hybrid Approach

This paper proposes a hybrid approach to the management of stakeholder conflicting expectations in higher education (HE) by combining Stakeholder Theory (ST) and a participatory approach. In this paper, we use an ex post facto approach to retrospectively report Sultan Qaboos University (SQU) experience in managing stakeholder conflicting expectations in developing the BA in English Language and Literature Program as a case study. We show that for an effective management of stakeholder conflicting expectations in HE, the three perspectives of ST (i.e., descriptive, instrumental and normative) have to be taken together as a unified approach with the normative perspective occupying the core. In addition, we argue that this unified approach should be complemented by a participatory approach to add an interactive dimension to stakeholder conflict management and allow stakeholders to become active conflict-solvers. The paper concludes that this hybrid approach is essential to manage stakeholder conflicting expectations in academic program development and to project academic program development in HE as a shared social responsibility

Negotiating Wikipedia narratives about the Yemeni crisis: Who are the alleged supporters of the Houthis?

In this article, the authors apply a narrative model to examine how narratives about the current crisis in Yemen are constructed on English Wikipedia. Using concepts from various narrative theories, as introduced to the field of translation studies by Baker’s Translation and Conflict: A Narrative Account (2006), they analyse an article published on English Wikipedia. The analysis, based on a narrative model designed for this study, focuses on the alleged supporters of the Houthis in the current Yemeni crisis and is applied to the talk pages and history pages associated with the article. The article concludes that, although Wikipedia writers appear free to write and edit without restrictions, they are in fact subject to strict policies and regulations. The transparency of their discussions is a striking feature that controls the quality of the narratives they negotiate on Wikipedia

SIGNIFICANCE OF METRICS IN SELECTION OF TALENTED FOR BASKETBALL

الاختيار في الجانب الرياضي يهدف الى اختيار افضل اللاعبين الشبان بهدف المشاركة بنشاط معين والوصول الى أعلى مستويات الأداء . نشأت فكرة البحث عن الناششين وذلك لاختلاف الناشئين بالخصائص البدنية ، الذهنية و النفسية . يعرف الاختيار بأنه عملية يتم من خلالها اختيار أفضل الرياضيين حسب قدراتهم ومناسبتها للرياضة . القياسات المترية توصف بانها قياسات عالمية ذات ارتباط عالي باللعبة ، وتخت هذه القياسات حسب اللعبة ، حيث ان كل لعبة لها متطلبات بدنية خاصة تختلف عن اللعبة الأخرى . هدف الدراسة هو اختيار لاعبين لم يتم اختيارهم بطريقة فنية بل على اساس قياسات بدنية ومن أجل التحقق من هذه الفرية قام الباحث بعمل قياسات لمجموعتين من الفئة العمرية (15،16،17) بكل من العراق وبولندا . وتوصلت نتيجة الدراسة الى أن القياسات البدنية كان لها ارتباط كبير باختيار اللاعبين وانجازهمIn general, selection in sports field targets the best youth to practice a certain activity to reach to a higher levels in such activity. The need arose for such process because of the differences of youth in their preparation physically, mentally and psychologically. Selection defined as (a process through which selection process of best athletes is carried out on multiple period based on the different stages of sports preparation). Metrics measurements considered as individual characteristics that highly linked to achievement of international sports levels, as each sports activity requires unique physical requirements differentiate it from other activities. The issue of research by notifying the Researcher of the selection of players does not carried out according to correct scientific basis in selecting the talents in basketball and that the Researcher used the descriptive approach by way of questionnaire, where the research sample consisted of the ages (15, 16 and 17) from Iraq and Poland. The Researcher carried out physical measurements on the research sample, selection of scoring from distance and that through research results, the Researcher concluded that physical measurements of great importance in the selection of player

Behaviour and fate of pesticides in plant-soil systems

No abstract available

Histopathological and biochemical effects of green tea and/or licorice aqueous extracts on thyroid functions in male albino rats intoxicated with dimethylnitrosamine

OBJECTIVE: To investigate histopathological and biochemical effects of green tea and/or licorice aqueous extracts in thyroid functions in male albino rats intoxicated with Dimethylnitrosamine. METHODS: 40 Male albino rats were divided into two main groups, 20 normal rats and 20 DMN intoxicated rats. Normal rats were subgrouped into 4 equal groups, group A without treatment (controls), group B treated with green tea, group C treated with licorice, group D treated with green tea and licorice. DMN intoxicated rats were subgrouped into 4 equal groups, group E treated with DMN, group F treated with DMN and green tea, group G treated with DMN and licorice, group H treated with DMN, green tea and licorice. The rats were permitted for free access to solubilized extracts of green tea and or licorice for 4 weeks. All rats in groups E, F, G, H were treated by intraperitoneal DMN (4 mg dissolved in 2.5 ml distilled water/kg body weight) seven times every 2 days in the first two weeks. Plasma total triiodothyronine and tetraiodothyronine were determined by radioimmunoassay. Thyroxine 5(-)monodeiodinase activity of liver was determined by spectrophotometeric method. Plasma thyroid stimulating hormone was determined by chemiluminometric technique. Histopathological examination was conducted. RESULTS: Histopathologically thyroid gland of DMN intoxicated rats showed degeneration (DG)and desquamation (DS) of the lining epithelium and atrophy of many acini with hyperemia (H) in the stromal capillaries and In comparison with control, the administration of DMN alone induced decrease in plasma levels of T3 and T4 while it induced increase in plasma levels of TSH and hepatic activity of Thyroxine 5(-)monodeiodinase. Coadminstration of DMN and green tea attenuated the lowering effect of DMN on plasma levels of T3 and T4 and induced increase in these levels but values are still below normal ones while Co administration of DMN with licorice or mixture did not affect these levels. Co administration of green tea and/or licorice with DMN attenuated the rising effect of DMN on hepatic activity of Thyroxine 5(-)-DI while augmented the rising effect of DMN on plasma level of TSH. CONCLUSION: Aqueous extract of green tea may be effective in amelioration of biochemical effects and histopathological lesions induced by DMN

The effect of Helicobacter pylori infection on gastric acid secretion in man

Helicobacter pylori (H pylori) infection is the commonest chronic bacterial infection world-wide. The work carried out in this thesis has sought to explore the effect of the infection on gastric secretory function in man. We developed a new test of gastric acid secretion using the substance gastrin releasing peptide (GRP) as the stimulus. Acid secretion measured in response to intravenous infusion of GRP reflects the combined functional response of the antrum and body of the stomach. It activates both stimulatory and inhibitory controls of acid secretion and in these respects it simulates the response to eating. The reproducibility of the GRP test was assessed and was found to be high for both gastrin and acid secretion. Using this new tool we studied acid secretion in a variety of subjects with and without H pylori infection. We have found that GRP stimulated acid secretion is increased six fold in DU patients with the infection compared to H pylori negative healthy volunteers (true normals). This exaggerated acid response is likely to represent a key pathophysiological defect which underlies DU disease. We have demonstrated for the first time that eradication of H pylori infection leads to normalisation of basal and GRP stimulated acid secretion in DU patients. These novel findings have shed considerable light on the understanding of the pathophysiology of DU disease and the role of H pylori infection in it. We have also shown for the first time that GRP stimulated acid secretion is increased two to three fold in H pylori positive healthy volunteers compared to true normals. This secretory abnormality also fully resolves following eradication of the infection. Since half the world's population is colonised with H pylori, it is essential that all future gastric secretory studies ensure that their control subjects are negative for the infection. The presence of the secretory abnormality in healthy volunteers may also be of relevance to other upper Gl diseases such as reflux disease. We proceeded to investigate the mechanism of the exaggerated acid response to GRP in DU patients and presented evidence compatible with this being due to impaired inhibitory control of acid secretion. We proceeded to examine the effect of the most commonly prescribed medication for dyspepsia, i.e. ranitidine, on acid secretion in healthy volunteers with and without H pylori infection. We showed that a two month course of ranitidine leads to a doubling of basal acid output and a 68% increase in GRP stimulated acid output two days after withdrawing treatment. This rebound acid hypersecretion is not associated with any significant change in gastrin concentrations and fully resolves within ten days of stopping ranitidine. These findings may offer an explanation for the common clinical problem of rapid resurgence of dyspeptic symptoms following discontinuation of acid suppressive therapy. Finally, we used the GRP test to study acid secretion in patients with non ulcer dyspepsia (NUD) and H pylori infection. We showed that a significant proportion of NUD patients had an exaggerated acid response to GRP similar to DU patients i.e. they displayed the DU diathesis. This raises the exciting possibility that this group of NUD patients may also be cured by eradication of their H pylori infection