21 research outputs found
Velocity measurements in multi-directional waves using a perforated-ball velocity meter
No full textA simple and robust device has been developed for measuring three-dimensional velocities in laboratory waves and other flows. It comprises two small perforated balls which have well-defined Morison drag and inertia coefficients. Solution of the ‘inverse Morison problem’ in three dimensions allows the ambient velocity to be computed from measurements of loading on the balls. This paper describes the calibration of the instrument, the algorithm for computing velocities from forces, and details of applications in a wave flume (where results are compared with measurements from an adjacent Laser-Doppler Anemometer) and in uni- and multi-directional waves in a basin (with comparisons from an electro-magnetic flowmeter and linear wave theory). Measurements are shown to agree very well with the other sources of data where appropriate, and suggest that the perforated-ball velocity meter has some advantages over more conventional instruments.<br/
Effects of wave directionality on the in-line loading of a vertical cylinder
No full textThis paper presents results from an experimental investigation into the loading on a rigid vertical circular cylinder in irregular unidirectional and multidirectional waves in water of uniform depth. The ambient flow at the location of the cylinder was measured directly using perforated-ball velocity meters (PVMs), in order to avoid uncertainties associated with the use of wave theories. Reynolds numbers were in the range of 104 to 7 X 104, and Keulegan-Carpenter numbers ranged from o to 16. In-line Morison coefficients and root-mean-square force coefficients are estimated from the loading measured on force sleeves at three elevations along the length of the cylinder. Results are presented for the probability distributions of forces and peak forces, and for Morison and rms force coefficients. Effects of wave directionality are compared with Dean's analytical predictions
Local forces on a vertical cylinder in regular and irregular waves
No full textThis paper presents results from an experimental investigation on the loading on a rigid slender vertical circular cylinder in undirectional regular and irregular waves. The ambient flow was measured directly, so that the derived results would not be subject to additional uncertainties associated with the use of wave theories. Morison drag, inertia and lift coefficients are computed from forces measured at one force sleeve and compared with data obtained at the same Reynolds and Keulegan Carpenter numbers, but under uniform flow conditions in a U-tube. In regular waves, the results show the importance of the non-uniformity of wave-induced flow, and in irregular waves it is clear that the loading is much influenced by the history of the flow.NRC publication: Ye
A comprehensive analysis of topics in measure theory, distribution theory and an introduction to Sobolev's theory of spaces
No full textEn esta monografía, son presentados los resultados de una recopilación bibliográfica, puntualmente el análisis y estudio de [Lieb and Loss, 1997] y [Kesavan, 1989]. Se trabajan cálculos y demostraciones que los autores omiten en cada texto y algunos ejercicios que son utilizados en el desarrollo de los temas, así como ejemplos y contraejemplos que ayudan a analizar mejor los resultados encontrados en estos. El Capítulo 1, está dedicado a los capítulos 1 y 2 de [Lieb and Loss, 1997] y en algunas secciones en específico. En éste, se aborda la teoría de la medida y propiedades de los espacios L p . En el Capítulo 2 se analizan los capítulos 1 y 2 de [Kesavan, 1989], allí se trabajó la teoría de distribuciones y una introducción a los espacios de Sobolev de orden entero.In this monograph, results of a bibliographic compilation are presented, punctually the analysis and research about [Lieb and Loss, 1997] and [Kesavan, 1989] . Calculations and demonstrations which the author omits in each text, are given and some exercises which are used, as well as examples and counterexamples that help to analyze better the results found in these ones. Chapter 1 is devoted to chapters 1 and 2 of [Lieb and Loss, 1997] and some specific sections. In this one, measure theory and properties of L p spaces is addressed. In chapter 2, chapters 1 and 2 of [Kesavan, 1989] are analyzed, here, the theory of distributions is treated and an introduction to Sobolev spaces of integer order.Magíster en MatemáticasMaestrí
Topochemical engineering of composite hybrid fibers using layered double hydroxides and abietic acid
No full textTopochemical engineering of hybrid materials is an efficient way of synthesizing hydrophobic and highly tensile fiber composites by utilizing the intermolecular hydrogen bonds in natural materials. These materials include wood pulp fibers, abietic acid (resin acid) and inexpensive metal salts. In this work, a hybrid composite was created using bleached and unbleached kraft pulp fibers as cellulose platform. In situ co-precipitation of layered double hydroxide (LDH) was performed to grow LDH crystals on the surface of the cellulose fibers, followed by the immobilization of abietic acid (AA) on LDH-grafted cellulose. Here we aimed to benefit from the hydrogen bonding between -OH groups of cellulose and LDH, and the -COOH groups of AA to obtain charge-directed assembly of one material on the other material. Thus, composite hybrid fibers (C-HF) were produced and then characterized by optical (CAM), spectroscopic (XRD, IR) and microscopic techniques (SEM) to determine their average length and distribution, structure and purity, bonding, and morphology. These fibers further were tested for water contact angle (hydrophobicity), oil absorption (lipophilicity), tensile strength and ISO brightness measurements. The performance of C-HF was compared with unmodified reference fibers (REF), fibers composed with only AA (C-F) and LDH-hybridized fibers (HF). The results revealed a variety of correlations between materials and their properties due to characteristic surface morphology, functional groups, hydrogen bonding and natural co-materials such as lignin and hemicelluloses. Attractive and repulsive van der Waals forces between material entities play a crucial role in the resulting properties.sponsorship: Author Liji Sobhana acknowledges Magnus Ehrnrooth Foundation for the post-doctoral financial support (2018). Lokesh Kesavan acknowledges the Turku Collegium for Science & Medicine (TCSM) and University of Turku for the funding aid and hosting his collaborative postdoctoral research. (Magnus Ehrnrooth Foundation, Turku Collegium for Science & Medicine (TCSM), University of Turku)status: Publishe
Numerical simulation of power consumption under the effect of reduced surface area of the DS furnace
No full textWrestling with Japanese Tribalism Emerging Collaborative Opportunities For India and Japan
No full textJapanese firms, with their strong technology base and high domestic factor costs, have the potential of teaming with India, with its more basic infrastructure and eight times the population. Japan's poorly-performing excess capital could fuel India's strongly-developing middle class and robust entrepreneurialism. Especially promising are collaborative information technology projects. What stands in the way of a greatly expanded relationship? Much of the blockage stems from Japan's insularism, an impetus here labeled tribalism. A hopeful dimension is that this tribalism can be clearly defined as archaic, recognized as detrimental, and then toned-down. Further points for development include an active campaign to encourage diversity in Japan, teaming up to provide alternatives to investment in neighboring China, and agitating for representation on the UN Security Council. India can help initiate all these processes, and can in turn benefit from a Japan reaching out for regional economic partnerships.homogeneity; tribalism; UN Security Council; partnership; immigration; trade; e-Japan strategy
Japanese defence policy since 1976: latest trends
No full textThis study sets Japan's defence posture in the context of world politics, especially in regard to the Soviet Union and the United States. The different perceptions of defence by different groups of people in Japan (the man on the street, the political parties and business groups) are discussed. The gradual development from a heavy dependence on the United States for defence is slowly progressing towards a more equal sharing of defence responsibilities between the United States and Japan. The author points out the practical necessities for this change, the pressures that the United States is putting on Japan to carry out this change, and also the problems and fears that arise in Japan because of this pressure. Specific topics covered include the development of defence production industries in Japan, the exchange of weapons technology with the United States, Japan's ability to defend her sea lanes, the concept of collective defence responsibility and the diverse opinions aroused both in Japan itself and in neighbouring countries in regard to these developments. The author has added an addendum since the publication of the 1983 Japanese Defence White Paper, the reaction to which again emphasises the difficulties Japanese defence planners and politicians face in trying to achieve a balanced defence policy
MR3157399 Reviewed: Kesavan, S. Continuous functions that are nowhere differentiable. Math. Newsl. 24 (2013), no. 3, 49–52. (54C05)
No full textThe author uses the Baire category theorem to prove the existence of nowhere differentiable functions in C([0,1]). Precisely, the author proves the following:
Theorem 1. There exist continuous functions on the interval [0,1] which are nowhere differentiable. In fact, the collection of all such functions forms a dense subset of C([0,1])
