Value Centric Approaches to the Design, Operations and Maintenance of Wind Turbines

Wind turbine maintenance is emerging as an unexpectedly high component of turbine operating cost, and there is an increasing interest in managing this cost. This thesis presents an alternative view of maintenance as a value-driver, and develops an optimization algorithm to evaluate the value delivered by different maintenance techniques. I view maintenance as an operation that moves the turbine to an improved state in which it can generate more power and, thus, earn more revenue. To implement this approach, I model the stochastic deterioration of the turbine in two dimensions: the deterioration rate, and the extent of deterioration, and then use maintenance to improve the state of the turbine. The value of the turbine is the difference between the revenue from to the power generation and the costs incurred in operation and maintenance. With a focus on blade deterioration, I evaluate the value delivered by implementing two different maintenance schemes, predictive maintenance and scheduled maintenance. An example of predictive maintenance technique is the use of Condition Monitoring Systems to precisely detect deterioration. I model Condition Monitoring System (CMS) of different degrees of fidelity, where a higher fidelity CMS would allow the blade state to be determined with a higher precision. The same model is then applied for the scheduled maintenance technique. The improved state information obtained from these techniques is then used to derive an optimal maintenance strategy. The difference between the value of the turbine with and without the inspection type can be interpreted as the value of the inspection. The results indicate that a higher fidelity (and more expensive) inspection method does not necessarily yield the highest value, and, that there is an optimal level of fidelity that results in maximum value. The results also aim to inform the operator of the impact of regional parameters such as wind speed, variance and maintenance costs to the optimal maintenance strategy. The contributions of this work are twofold. First, I present a practical approach to wind turbine valuation that takes operating and market conditions into account. This work should therefore be useful to wind farm operators, investors and decision makers. Second, I show how the value of a maintenance scheme can be explicitly assessed for different conditions

Phytochemical Constituents and Pharmacological Activities of Calendula officinalis Linn (Asteraceae): A Review

Calendula officinalis Linn. (Asteraceae) is used medicinally in Europe, China and India amongst several places in the world. It is also known as “African marigold” and has been a subject of several chemicaland pharmacological studies. It is used in traditional medicine, especially for wound healing, jaundice, blood purification, and as an antispasmodic. Chemical studies have underlined the presence of variousclasses of compounds, the main being triterpenoids, flavonoids, coumarines, quinones, volatile oil, carotenoids and amino acids. The extract of this plant as well as pure compounds isolated from it, have been demonstrated to possess multiple pharmacological activities such as anti-HIV, cytotoxic, antiinflammatory, hepatoprotective, spasmolytic and spasmogenic, amongst others. In this review, we have explored the phytochemistry and pharmacological activities of C. officinalis in order to collate existinginformation on this plant as well as highlight its multi-activity properties as a medicinal agent. This is as a result of the worldwide cultivation of the plant and increasing published reports on it

The Antioxidant Activity of the Leaves of Barleria grandiflora Dalz. (Acanthaceae)

Aqueous and hydro alcoholic extracts of the leaves of Barleria grandiflora Dalz. were evaluated for the antioxidant activity by the FTC and TBA methods. The results obtained in the present study indicate that the leaves of Barleria grandiflora are potential source of natural antioxidants. Initial phytochemical screenings of the extracts have shown the presence of flavanoids, tannins, saponins, carbohydrates and aminoacid

In-Vitro Evaluation of Anti-Bacterial and Anti-Fungal Activity of Vitex nigundo (Verbenaceae)

Vitex negundo belongs to the family Verbenaceae. It is a large aromatic shrub distributed throughout the greater part of India up to an altitude of 1500 m in the outer Himalayas. It is widely planted as a hedge plant along the roads and between the roads. Traditionally it is having the flok claims like useful in treatment of rheumatism, insecticidal, antimicrobial, anticancer, tranquillizer, tonic, febrifuge, expectorant and diuretic properties. In the present study an attempt had been made to evaluate comparative antibacterial and antifungal principles from Vitex nigundo with some therapeutically used antibiotics. Different extracts of Vitex negundo leaves were investigated for its anti microbial and antifungal activity on five bacterial species and three fungal species these are Staphylococcus aureus, Proteus vulgaris, Bacillus subtilis, E.coli, Pseudomonas aerugenosa and Aspergillus niger, Aspergillus flavon, Candida albicans respectively. Among all extracts waterethanol (50:50) extract showed maximum anti microbial and water extract showed maximum antifungal activity against all tested species

Pharmacognostical and phytochemical studies on roots of Bombax ceiba Linn. [Estudios farmacognóstico y fitoquímico de las raíces de Bombax ceiba Linn.]

Abstract Resumen Context: Bombax ceiba Linn. (Bombacaceae) is a well-known plant for its antihypertensive, antioxidant, antidiabetic, aphrodisiac and uterine tonicity properties. Aims: To study pharmacognostical, physicochemical and phytochemically the roots of this plant. Methods: Pharmacognostical study included the macroscopic characters like size, color, surface characteristics, texture, fracture characteristics and odor of the roots. The intact root as well as powdered drug were studied under a microscope to analyze the cellular characteristics of the drug. Physicochemical parameter like extractive values, loss on drying (LOD), total ash, water-soluble and acid insoluble ash, foaming index and hemolytic index of Bombax ceiba root powder were determined as per WHO guidelines. Preliminary phytochemical screening and qualitative chemical examination studies have been carried out for the various phytoconstituents. HPTLC have also carried out using cyclohexane: diethyl ether: ethyl acetate as mobile phase. Results: Chemical evaluation and TLC studies shown presence of alkaloids, glycosides, flavonoids, steroids, saponins and tannins. The microscopic characters have shown presence of cork, cambium, xylem vessels, stone cells, starch grains, calcium oxalate crystals and phloem fibers. Microscopy analysis of the powder included the cork cells, fibers, calcium oxalate crystals and vessel. The presence of steroids was confirmed in HPTLC fingerprinting studies. Conclusions: Pharmacognostical and preliminary phytochemical screening of Bombax ceiba roots will be useful in order to authenticate, standardize and avoid any adulteration in the raw material. The diagnostic microscopic characters and physicochemical data will be helpful in the development of a monograph. The chromatographic fingerprinting profile can be used to standardize extracts and formulations containing Bombax ceiba roots. Contexto: Bombax ceiba Linn. (Bombacaceae) es una planta conocida por sus propiedades anti-hipertensiva, antioxidante, antidiabética, afrodisíaca y tónica uterina. Objetivos: Estudiar farmacognóstica, fisicoquímica y fitoquímicamente las raíces de esta planta. Métodos: El estudio farmacognóstico incluyó los caracteres macroscópicos como tamaño, color, características de la superficie, textura, características de fractura y el olor de las raíces. La raíz intacta y la droga en polvo se estudiaron bajo el microscopio para analizar las características celulares de la droga. Los parámetros fisicoquímicos como valores extractivos, pérdida por desecación (LOD), cenizas totales, índice de formación de espuma soluble en agua y cenizas insolubles en ácido, y el índice hemolítico del polvo de raíz de Bombax ceiba se determinaron según directrices de la OMS. Se realizaron estudios de tamizaje fitoquímico preliminar y examen químico cualitativo para los distintos fitoconstituyentes. También se realizó el estudio por HPTLC usando como fase móvil ciclohexano: éter dietílico: acetato de etilo. Resultados: La evaluación química y los estudios de TLC mostraron presencia de alcaloides, glucósidos, flavonoides, esteroides, saponinas y taninos. Los caracteres microscópicos han demostrado la presencia de corcho, cambium, vasos del xilema, células pétreas, granos de almidón, cristales de oxalato de calcio y fibras del floema. El análisis microscópico del polvo incluyó las células de corcho, fibras, cristales de oxalato de calcio y vaso. La presencia de esteroides se confirmó en estudios de huellas por HPTLC. Conclusiones: El tamizaje farmacognóstico y fitoquímico preliminar de las raíces de Bombax ceiba será útil para autenticar, estandarizar y evitar cualquier adulteración en la materia prima. Los caracteres microscópicos de diagnóstico y los datos fisicoquímicos serán útiles en el desarrollo de una monografía. El perfil cromatográfico de huellas (fingerprinting) puede utilizarse para estandarizar extractos y formulaciones que contengan raíces de Bombax ceiba

IN VITRO ANTIOXIDANT ACTIVITY AND QUANTITATIVE ESTIMATION OF PHENOLIC CONTENT OF LAGENARIA SICERARIA

ABSTRACT The plant, Lagenaria siceraria (Family: Cucurbitaceae), known as bottle gourd, Calabash, Doodhi, and Lauki, is a common fruit vegetable used throughout the India. The antioxidant activities of different concentrations of ethanol extracts of fruits of Lagenaria siceraria the were determined by the four assay techniques i.e. DPPH radical scavenging assay, Reducing power ability, Hydrogen peroxide scavenging assay and thiocyanate method. Ethanol extract of fruits of Lagenaria siceraria has shown effective antioxidant activity in all assay techniques. The results obtained in the present study indicate that the fruits of Lagenaria siceraria are a potential source of natural antioxidants

Maintenance Optimization and Inspection Planning of Wind Energy Assets: Models, Methods and Strategies

Designing cost-effective inspection and maintenance programmes for wind energy farms is a complex task involving a high degree of uncertainty due to diversity of assets and their corresponding damage mechanisms and failure modes, weather-dependent transport conditions, unpredictable spare parts demand, insufficient space or poor accessibility for maintenance and repair, limited availability of resources in terms of equipment and skilled manpower, etc. In recent years, maintenance optimization has attracted the attention of many researchers and practitioners from various sectors of the wind energy industry, including manufacturers, component suppliers, maintenance contractors and others. In this paper, we propose a conceptual classification framework for the available literature on maintenance policy optimization and inspection planning of wind energy systems and structures (turbines, foundations, power cables and electrical substations). The developed framework addresses a wide range of theoretical and practical issues, including the models, methods, and the strategies employed to optimise maintenance decisions and inspection procedures in wind farms. The literature published to date on the subject of this article is critically reviewed and several research gaps are identified. Moreover, the available studies are systematically classified using different criteria and some research directions of potential interest to operational researchers are highlighted

Effect of Chlorophytum borivilianum on adjuvant induced arthritis in rats

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