2,938 research outputs found
Simple drag prediction strategies for an Autonomous Underwater Vehicle’s hull shape
No full textThe range of an AUV is dictated by its finite energy source and minimising the energy consumption is required to maximise its endurance. One option to extend the endurance is by obtaining the optimum hydrodynamic hull shape with balancing the trade-off between computational cost and fluid dynamic fidelity. An AUV hull form has been optimised to obtain low resistance hull. Hydrodynamic optimisation of hull form has been carried out by employing five parametric geometry models with a streamlined constraint. Three Genetic Algorithm optimisation procedures are applied by three simple drag predictions which are based on the potential flow method. The results highlight the effectiveness of considering the proposed hull shape optimisation procedure for the early stage of AUV hull desig
THE CORRELATION OF THE MEDIEVAL EUROPEAN STATE AND LAW IN THE DOCTRINE OF P.A. KROPOTKIN
No full textThe actual task of Russian state studies and jurisprudence remains the opposition to the ideological and theoretical constructions of Russian classical anarchism. Purpose: to establish the most significant features and disadvantages of P.A. Kropotkin’s interpretation of the correlation of state and law on the example of Medieval Europe. When writing the article, the author applies interdisciplinary and class approaches. General scientific and specific scientific methods are used: historical, problem-theoretical, formal-logical, textual. Materials: monuments of law, other historical sources, foreign and national historiography. The analysis shows that P.A. Kropotkin’s works are characterised not only by a pronounced anti-exploitation pathos, but also by an equally pronounced tendentiousness. Results: aprioriism, anti-statism and antilegism, radical localism, Eurocentrism, diffusionism, cyclism and catastrophism, clothed in the form of postulates, predetermined P.A. Kropotkin’s one-sided interpretations of the interaction of the medieval European state with positive and customary law. In the first case, it took a purely causative form, and in the second, it was predominantly conflictual. These are the key flaws of P.A. Kropotkin’s correlation concept
Flow-induced gate vibrations: Prevention of sef-excitation computation of dynamic gate behaviour and the use of models
No full textThe objective of this study is to develop design criteria for the dynamic behaviour of gates and valves. To this end, a resume of existing theories is given as well as an extended analysis of the added water mass, hydrodynamic rigidity and damping (also negative damping or self-excitation) and excitation by turbulent flow. New computation methods are presented for self-exciting vibrations: The ensuing introduction of an instability indicator permits the prediction of such vibrations in the design phase. Methods are described to calculate the added water mass and water damping in flowing water. Also treated are the instability of overflowing and falling water nappes, the response of a mass-spring system to noise excitation by turbulence, and the technique of hydroelastic models. Prior publications by the author on these subjects are to be found in the Appendices.Hydraulic EngineeringCivil Engineering and Geoscience
Quality and qualities of design studies, design research and design
No full textGreen Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Methodologie en Organisatie van Desig
Views of P.A. Krushevan on the National Problem in Russia: Moldavian or Russian Nationalist
No full textThe article deals with the national identity of P.A. Krushevan. Being of Moldavian nationality, he was a Russian conservative writer and journalist. At the beginning of the 19th century he served as a Russian nationalist in the political arena. The author shows that he was a supporter of Moldavian national traditions and a personality of the Moldavian national movement. At the same time Krushevan was an «imperial nationalist» and a Russian statesman. In behalf of Bessarabia peasants, he exposed the economic activity of «plutocracy», but he was a stranger to domestic anti-Semitism
The Nigerian Co-operative Law: Taking the Baton from P.A. Oluyede
No full textSome of the challenges hindering the development of co-operatives and their governing laws in Nigeria are the inadequacy of literature, and the lack of standardized classification on the subject of co-operative law. With the aim to identify and espouse relevant literature on the subject matter, this paper seeks to collect, collate and review the relevant literature. A classic was identified in the work of P.A. Oluyede (1988) Nigeria Administrative Law, in chapter four, entitled “Public Corporations, and Public Enterprises.” Among other findings, the learned author dedicated the chapter to the historical development of Nigerian co-operative societies and their governing laws, situated cooperatives as public enterprises, and made recommendations. Furthermore, it was observed that there have been few contributions within the annals of the Nigerian academic and research community on co-operative law. Thus, Oluyede’s classics retains its position as a primary reference material for the modernization of the Nigerian cooperative law and sets the path for its standardization. However, supposedly consequential development has remained elusive, hence the imperatives to build on some of the positions espoused in Oluyede’s chapter in view of current realities. Although P.A Oluyede’s contribution retains its position as a top-notch reference material, some of the positions canvassed are no longer applicable to Nigerian co-operatives, hence the need to review Nigerian cooperative law as recommended. 
Sulphurised lipids in sediments: The key to reconstruct palaeobiochemicals and their origin
No full textApplied Science
Aromatic moieties in geomacromolecules: Structure, origin and significance
No full textApplied Science
Colonic locomotion
No full textThe most effective screening method for colonic cancer is colonoscopy. However, colonoscopy cannot be easily embraced by the population because of the related pain intensity. Robotic devices that pull themselves forward through the colon are a possible alternative. The main challenge for such devices is their locomotion method along the slippery colon. This study focuses on devices which regularly switch between high friction to grip and low friction to slide and introduces a new method to manipulate friction by means of mucoadhesives. Mucoadhesives are polymers adhering to the mucus that covers the intestinal surface. We showed experimentally that mucoadhesive films can generate high static friction with the colon. In contrast with Coulomb friction, the static friction increases with the film area. The film geometry is of influence as well. Strikingly, when reducing the area by opening holes within the film structure, static friction can be considerably increased. A theoretical model was developed to express the frictional behaviour of mucoadhesive films. The role of geometry in the static friction offers new outlets to friction manipulation and provides new options for the design of the device. It seems also feasible to expand and apply the idea of increasing and manipulating friction by means of adhesive forces when gripping or handling soft, sensitive, or vulnerable objects. The artifice is to increase the adhesive forces up to a level that friction starts being controlled by adhesion, but without exceeding a ceiling of forces beyond which the adhesive falls into the area of permanent joints.Mechanical Maritime and Materials Engineerin
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