Active filters: A unified approach

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The increase in the occurrence of non-linear loads in power systems has caused considerable concern to power utilities and manufacturers of power electronics equipment. To alleviate the problems caused by generation of current harmonics, there has been considerable interest in the use of active filters. This thesis presents a unified approach to the design of active filter configurations. It is shown that this approach offers a systematic method of classifying existing structures and it can be used for developing new circuits.Funding was obtained from the Iranian Ministry of High Education

Hierarchical Clustering Approach for Product Variety Management

Continually evolving customer’s needs has contributed to an increase in demand for product variety over the recent decades. Proliferation of product variants affects different aspects of product life cycle which increases the complexity of managing product variety. In this context, the notion of grouping and classification based on similarity within a family of product is the key in managing product variety. This research proposes hierarchical clustering as solution approach that is intuitively relevant and it focuses on progressively grouping the elements that share high similarity with each other. In this research, three types of product variety-related problems are investigated. The first problem concerns with designing product architecture in a way to support product variety. Design Structure Matrix (DSM) is used to visualize product architecture and to develop a new matrix-based clustering approach based on hierarchical cluster analysis. The challenge is that there are numerous possible product architectures even for a product with few components. One unique advantage of the proposed method lies in supporting “overlapping components” which is not directly addressed by the conventional techniques in cluster analysis. The second problem focuses on structuring supply chain network in case of product variety that indicates the precedence orders of suppliers and sub-assemblers. The challenge is that the number of possible structures of supply chain network grows dramatically with the increase in the number of product variants. The solution approach is based on hierarchical clustering, in which the tree structure is applied to construct the supply chain network. The core technique is to investigate the coupling values between the module variants and characterizing the grouping condition in the structuring process. The third problem is to develop semi-finished products to reduce production costs. The challenge is that the possible solution space can increase exponentially with increase in the number of elements (e.g. components) in the problems. In the solution approach, the basic information of product variety is captured in a matrix format, specifying the component requirements for each product variant. Then, hierarchical clustering is applied over the components with the consideration of demands. The key stage is similarity analysis, in which problem-specific information can be incorporated in the clustering process. In summary, the proposed method can be a practical tool for tackling product variety-related problems. It yields good quality results in a limited time. Thus, it can be used to obtain better results than other algorithms when the amount of time available to perform the task is limited

Determination of the Temperature Response Curves for Abscisic Acid and its Derivatives in Economically Important Horticultural Crops

Part I Four-week old tomato (Lycopersicon esculentum Mill.) seedlings were exposed to different constant temperatures of 15, 25, 35, or 45 c. To determine the effect of temperature on Abscisic Acid (ABA) young and old leaves were harvested at 0, 6, 12, 24, or 48 hand free, hydrolyzable and total ABA were measured using gas liquid chromatographic methods. Temperature had a significant effect on free, hydrolyzable and total ABA in both young and old leaves. Time had a significant effect as a cubic function on all ABA measurements in old leaves but in young leaves a significant effect was observed only on the hydrolyzable ABA. Interactions between temperature and time were observed in both young and old leaves. Young leaves had significantly higher amounts of free and hydrolyzable ABA than did old leaves. The total ABA levels were not significantly different in young and old leaves. Suboptimal temperatures increased ABA levels in the plants, in a manner similar to that of other kinds of stresses. Part II Five- week old tomato plants (Lycopersicon esculentum Mill.) were exposed to day-night temperatures of 10-5, 15-10, 25 - 15, 35-25, or 45-35 C. The day length was 16 h with a light intensity of approximately 400 µ E m-2s-1. Plant tops were sampled at 12, 24, 48, 68, or 72 h. Free, hydrolyzable and total absciscis acid (ABA) quantities were measured using standard gas chromatographic techniques. Stressful temperatures significantly increased both free and hydrolyzable ABA levels. The highest ABA levels were observed in plants grown at 10-5 C. Although time significantly affected ABA levels, its role needs more precise definition. Due to the similar involvements of ABA in temperature-induced and other stresses, ABA may be hypothesized to be a common mediator for different stresses. Part III Warm season crops: bean (Phaseolus vulgaris) CV. Burpee Stringless Green Pod; corn (Zea mays) CV. Golden,Jubilee; Cantaloupe (Cucumis melo) cv. Hales Best; eggplant (Solunum melongena) CV. Ichiban; and okra (Hibiscus esculentus) CV. Dwarf Green and cool season crops: beet (Beta vulgari s) CV. Early wonder; lettuce (Lactuca sativa) •CV. Great Lakes; cabbage (Brassica oleracea) cv. Savoy; radish (Raphanus sativus) CV. Scarlet Globe; and pea (Pisum sativum) cv. Little Marvel were exposed to 10, 25, or 40 C. After 24 h free and hydrolyzable ABA and DPA were measured in the plant tops using standard gas chromatographic methods. Warm season crops exhibited elevated levels of PABA, HABA and DPA under 10 C, compared to those at 25 or 40 c. Cool season crops showed similar PABA, HABA and DPA contents under all temperatures, except pea which had higher PABA and HABA levels at 40 C and beet which showed lower levels of HABA at 25 C as compared to 10 and 40 C. DPA existed at much higher concentrations than ABA in all plants of the two groups. It is concluded that while 1 0 C is stressful to warm season crops and thus the ABA and DPA increases, it is not so favorable to cool season crops. A temperature of 40 C would be stressful to both groups, but as long as water supply to the plant is not limiting the plants would not actively produce ABA. Higher levels of DPA under stressful conditions would warrant consideration and taking into account the role of metabolism in regulation of total ABA in the plant

A Case Report of the Rare Disease of Pseudoainhum at Kerman Afzalipour Hospital, Iran

Abstract: Background & Aims: Pseudoainhum is a rare acquired or congenital disorder characterized by progressive development of a fibrotic band on a finger or toe until spontaneous autoamputation occurs. The various etiological hypotheses given for this disease include infectious (mycosis, mycobacteria), traumatic (plants), vascular (andysplasia), neurological (polyneuritis), and genetic (keratodermia) mechanisms. Ainhum predominantly affects black people living in west Africa, south America, and India. Case presentation: A 12 year old girl from Chahrigan Harirabad, a village near Kahnooj, Iran, with low socioeconomic status whose parents were not related, presented with autoamputated right foot toes. According to her mother she was in her usual state of good health until 1 year of age, when she developed a deep painless wound in the base of the fifth toe of the right foot. The depth of the wound progressed over time until it autoamputed. The same process happened to the 2nd, 3rd, and 4th toes of the same foot. On physical examination the pulse of the posterior tibialis artery was too weak and there was no detectable pulse of the dorsalis pedis artery. All examinations of toes of the left foot were normal. There was also a kyphoscoliosis toward the left side. The laboratory tests were normal; however, triphasic Doppler sonography showed a decreased velocity of blood flow in the distal part of the anterior tibialis artery. Conclusion: Due to the rarity of the disease and genetics being the most important contributing factor, we suggest a genetic study of this patient and her family members, regular follow up, and physical examination of the patient. We also suggest that with promotion of the level of hygiene and adequate education we can prevent further damage in this patient, as trauma and subsequent infection are the likely predisposing factors. Keywords: Pseudoainhum, Autoamputation, Dorsalis pedis artery, Anterior tibialis artery » XM

Iniciando a eternidade: história e mito em El Evangelio según San Marcos, de Jorge Luis Borges

O presente artigo analisa o conto El Evangelio Según San Marcos, do escritor argentino Jorge Luis Borges, buscando localizar em sua estrutura alguns dos sentidos possíveis impressos pelo escritor ao processo de modernização portenho. Desse modo, uma leitura a contrapelo não somente do significado das “margens” do tecido urbano, senão igualmente do “mito” em oposição ao movimento histórico, constitui, a nosso ver, a chave de entendimento para a realização de um projeto estético que é, também, um projeto de decifração de uma realidade cindida na periferia latino-americana

O dilema da forma: o realismo e o maravilhoso em Alejo Carpentier e Mia Couto

O presente artigo visa fazer uma reflexão sobre o conceito de realismo maravilhoso e sua utilização em dois romances específicos: Los Pasos Perdidos (1953), do cubano Alejo Carpentier, e O Outro Pé da Sereia (2006), do moçambicano Mia Couto. Para tanto, analisaremos a noção de realismo, tal qual expressa por György Lukács, a fim de pensar as condições de sua consecução na periferia do capitalismo. A isto deve se somar o maravilhoso, como característica reveladora da especificidade do realismo latino-americano, bem como das diferenças entre este e a ficção de Couto

A PERSISTÊNCIA DO REAL: AS CONDIÇÕES DO REALISMO NO ROMANCE DA PERIFERIA DO CAPITALISMO

O presente artigo tem o objetivo de analisar algumas concepções teóricas sobre o realismo na literatura, principalmente aquelas relacionadas ao contraste Europa-Estados Unidos e territórios periféricos, como a América Latina. Há, portanto, um esforço por iniciar um diálogo com o crítico norte-americano Fredric Jameson e seus comentários sobre o comportamento cultural. Este artigo aborda sua filosofia da história da arte que afirma a sequência realismo-modernismo-pós-modernismo para propor a seguinte questão: quando se trata do romance, seu desenvolvimento no centro do capitalismo pode ser reproduzido em trabalhos latino-americanos ao longo do mesmo período? Na tentativa de responder a essa pergunta, investigamos os “determinantes sociais do pensamento” que poderiam nos guiar até uma perspectiva satisfatória

Nós ainda não matamos ninguém – Opressão e violência em O Cão-Tinhoso, de Honwana

O presente artigo visa analisar as representações da opressão e da violência no universo colonial português, construído por Luís Bernardo Honwana em seu conto “Nós Matamos o Cão-Tinhoso”. Para isso, são investigadas principalmente as relações de poder entre as personagens Ginho, Isaura, Quim e Cão-Tinhoso