Overcoming the supply inconsistencies of tidal current energy conversion devices

The adoption of a sustainable approach to meeting the energy needs of society has recently taken on a more central and urgent place in the minds of many people. There are many reasons for this including ecological, environmental and economic concerns. One particular area where a sustainable approach has become very relevant is in the production of electricity. The contribution of renewable sources to the energy mix supplying the electricity grid is nothing new, but the focus has begun to move away from the more conventional renewable sources such as wind and hydro. The necessity of exploring new and innovative sources of renewable energy is now seen as imperative as the older forms (i.e. hydro) reach the saturation point of their possible exploitation. One such innovative source of energy currently beginning to be utilised in this regard is tidal energy. The purpose of this thesis is to isolate one specific drawback to tidal energy, which could be considered a roadblock to this energy source being a major contributor to the Irish national grid. This drawback presents itself in the inconsistent nature in which a tidal device generates energy over the course of a 24 hour period. This inconsistency of supply can result in the cycling of conventional power plants in order to even out the supply, subsequently leading to additional costs. The thesis includes a review of literature relevant to the area of tidal and other marine energy sources with an emphasis on the state of the art devices currently in development or production. The research carried out included tidal data analysis and manipulation into a model of the power generating potential at specific sites. A solution is then proposed to the drawback of inconsistency of supply, which involves the positioning of various tidal generation installations at specifically selected locations around the Irish coast. The temporal shift achieved in the power supply profiles of the individual sites by locating the installations in the correct locations, successfully produced an overall power supply profile with the smoother curve and a consistent base load energy supply. Some limitations to the method employed were also outlined, and suggestions for further improvements to the method were made.

Design of a bifurcated stent graft, with its accompanying delivery system.

Abdominal Aortic Aneurysms (AAA) haemorhaging is a life-threatening disease. An aneurysm is a permanent swelling of an artery due to a weakness in its wall. Current surgical repair involves opening the chest or abdomen, gaining temporary vascular control of the aorta and suturing a prosthetic graft to the healthy aorta within the aneurysm itself The outcome of this surgical approach is not perfect, and the quality of life after this repair is impaired by postoperative pain, sexual dysfunction, and a lengthy hospital stay resulting in high health costs. All these negative effects are related to the large incision and extensive tissue dissection. Endovascular grafting is an alternative to the standard surgical method. This treatment is a less invasive method of treating aortic aneurysms. It involves a surgical exposure of the common femoral arteries where the stent graft can be inserted through by an over-the-wire technique. All manipulations are controlled from a remote place by the use of a catheter and this technique avoids the need to directly expose the diseased artery through a large incision or an extensive dissection. The proposed design method outlined in this project is to develop the endovascular approach. The main aim is to design an unitary bifurcated stent graft (1 e- bifurcated graft as a single component) to treat these Abdominal Aortic Aneurysms. This includes the delivery system and deployment mechanism necessary to first accurately position the stent graft across the aneurysm sac and also across the iliac bifurcation, and secondly fix the stent graft in position by using expandable metal stents. Thus, excluding the aneurysm from the circulation and therefore preventing rupture. Miniaturisation is a critical aspect of this design, as the smaller the crimped stent graft the easier to guide through the vascular system to the desired location. Biocompatibility is an important aspect. The preferred materials for this prosthesis are to use Shape Memory Alloys for the stent and a multifilament fabric for the graft. A taper design is applied for the geometry as this gives a favourable flow characteristic and reduced wave reflections. Adequate testing of the stent graft to prove its durability and the ease of the method of deployment is a prerequisite. A bench test facility has being designed and build to replicate the cardiovascular system and the disease in question aortic aneurysms at the iliac bifurcation. The testing here shows the feasibility of the proposed delivery system and the durability of the stent graft across the aneurysm sac. Finally, these endovascular treatments offer the economic advantage of short hospital stays or even treatment as an outpatient, as well as elimination of the need for postoperative intensive care The risk of developing an aneurysm increases with age, that is one of the mam reasons to look for less invasive ways of treating aneurysms. Consequently, there is enormous pressure to develop and use these devices rapidly.

Experimental investigation of heat transfer characteristics from arrays of free impinging circular jets and hole channels

Free Tube Jet - Impingemenet - Heat Transfer - Arrary - Infrared Techuique - Hole Channels - Heat Transfer Uniformaty

Data Processing at the Flaw Detector with Combined Multisector Eddy-Current Transducer

There is described data processing at the flaw detector with combined multisectional eddy-current transducer and heterofrequency magnetic field. The application of this method for detecting flaws in rods and pipes under the conditions of significant transverse displacements is described.

Current classification and family-group names in Staphyliniformia (Coleoptera) / Alfred F. Newton, Jr., Margaret K. Thayer.

n.s. no.67(1992)

Galictis cuja (Mammalia): an update of current knowledge and geographic distribution

The lesser grison (Galictis cuja) is one of the least-known mustelids in the Neotropics, despite its broad range across South America. This study aimed to explore current knowledge of the distribution of the species to identify gaps in knowledge and anticipate its full geographic distribution. Eighty-nine articles have mentioned G. cuja since 1969, but only 13 focused on the species. We generated a detailed model of the species' potential distribution that validated previous maps, but with improved detail, supporting previous southernmost records, and providing a means of identifying priority sites for conservation and management of the species.

Current Account imbalances, thriftiness and the real exchange rate in a growing economy

This paper analyses the theoretical relevance of the dynamical aspects of growth on the discussion about the observed positive correlation between per capita real income and real exchange rates. With this purpose, we develop a simple exogenous growth model where the internal, external and intertemporal equilibrium conditions of a typical macroeconomic model are imposed; this last one through the inclusion of a balanced growth path for the foreign assets accumulation. The main result under this consideration is that the relationship defended by the Balassa-Samuelson hypothesis is no more so straightforward. In our particular approach, the mentioned bilateral relationship depends on a parameter measuring thriftiness in the economy. Therefore, the probability of ending up with a positive relationship between growth and real exchange rates -as the classical economic theory predicts- will be higher when the economy is able to maintain a minimum saving ratio. Moreover, given that our model considers a simple Keynesian consumption function, some explosive paths can also be possible.

La raó circular

És un text epistemològic sobre les qüestions cognitives circulars que apareixen: a) Quan el subjecte forma part de l’objecte estudiat; b) En la recerca de les bases del coneixement; c) Al voler justificar la inducció; d) En algunes interpretacions filosòfiques i científiques. S’hi explica l’estat del punt a) el més problemàtic, i s’aclareixen els altres tres punts: els b) i c) pel fet científic que l’evolució cognitiva humana ha anat acoblada a l’evolució biològica, la qual ha generat els a priori kantians i altres innatismes. El d) perquè la formació del coneixement i de la ciència es progressiva, passant una i altra vegada sobre el que ja s’havia tractat però ascendint alhora i ampliant el panorama, tal com fa una escala de cargol.

Clean Development Mechanism and Sustainable Development: a discussion on the link between the CDM and Sustainable Development, an analysis of the current status of the CDM portfolio, and an multicriteria evaluation of the effects of additional incentives in order to foster broad local Sustainable Development dividends from the CDM projects

vegeu resum en el fitxer adjunt a l'inici del treball de recerca

Assessment of current anglo-saxon proposals about criminal justice and the justification of legal punishment: Moore, Duff and Finnis on retribution, and the challenging compatibility with the up-and-coming Restorative Justice

Pendent

Biological materials in colorectal surgery: current applications and potential for the future.

Biological materials are increasingly used in abdominal surgery for ventral, pelvic and perineal reconstructions, especially in contaminated fields. Future applications are multi-fold and include prevention and one-step closure of infected areas. This includes prevention of abdominal, parastomal and pelvic hernia, but could also include prevention of separation of multiple anastomoses, suture- or staple-lines. Further indications could be a containment of infected and/or inflammatory areas and protection of vital implants such as vascular grafts. Reinforcement patches of high-risk anastomoses or unresectable perforation sites are possibilities at least. Current applications are based mostly on case series and better data is urgently needed. Clinical benefits need to be assessed in prospective studies to provide reliable proof of efficacy with a sufficient follow-up. Only superior results compared with standard treatment will justify the higher costs of these materials. To date, the use of biological materials is not standard and applications should be limited to case-by-case decision.

Development and current use of parenteral nutrition in critical care - an opinion paper.

Critically ill patients depend on artificial nutrition for the maintenance of their metabolic functions and lean body mass, as well as for limiting underfeeding-related complications. Current guidelines recommend enteral nutrition (EN), possibly within the first 48 hours, as the best way to provide the nutrients and prevent infections. EN may be difficult to realize or may be contraindicated in some patients, such as those presenting anatomic intestinal continuity problems or splanchnic ischemia. A series of contradictory trials regarding the best route and timing for feeding have left the medical community with great uncertainty regarding the place of parenteral nutrition (PN) in critically ill patients. Many of the deleterious effects attributed to PN result from inadequate indications, or from overfeeding. The latter is due firstly to the easier delivery of nutrients by PN compared with EN increasing the risk of overfeeding, and secondly to the use of approximate energy targets, generally based on predictive equations: these equations are static and inaccurate in about 70% of patients. Such high uncertainty about requirements compromises attempts at conducting nutrition trials without indirect calorimetry support because the results cannot be trusted; indeed, both underfeeding and overfeeding are equally deleterious. An individualized therapy is required. A pragmatic approach to feeding is proposed: at first to attempt EN whenever and as early as possible, then to use indirect calorimetry if available, and to monitor delivery and response to feeding, and finally to consider the option of combining EN with PN in case of insufficient EN from day 4 onwards.