Design, Prototyping and Testing of a Rotating Electrical Machine with Linear Geometry for Shipboard Applications

Conventional rotating electrical machines are characterized by stator and rotor structures featuring a cylindrical geometry around the shaft rotational axis. Although advantageous for mechanical reasons, the cylindrical geometry results in overall machine shapes and dimensions that may be unsuitable for installation. This particularly occurs in shipboard applications, where electric motors and generators are subject to stringent room constraints and need to be fit in unusually shaped compartments. This paper presents the development and test of a dual-shaft rotating permanent-magnet electric machine prototype having a linear structure that facilitates its onboard use for such applications as electric propulsion and rudder actuation. In fact, the proposed machine topology has overall dimensions which can be adjusted to fit the space available for installation. The operating concept and the detailed electromechanical design of the machine are first described. Then the manufacturing and factory test of the prototype under inverter supply are illustrated. Finally, the validation of the prototype as a boat propulsion variable-speed inverter-fed motor is presented. It is proved that, despite of its highly non-conventional electromechanical design, the machine can be effectively fed from a general-purpose inverter for permanent magnet motors

Contraction stress, elastic modulus, and degree of conversion of three flowable composites.

The aim of this study was to measure the contraction stress of three flowable resin composites and to correlate the stress with the elastic modulus and the degree of conversion. One low-shrinkage (Venus Diamond Flow) and two conventional (Tetric EvoFlow and X-Flow) flowable composites were polymerized for 40s with a light-emitting diode (LED) curing unit. Contraction force was continuously recorded for 300s using a stress-analyser, and stress values were calculated at 40s and at 300s. The maximum stress rate was also calculated for each specimen. The elastic modulus of each composite was assayed using a biaxial flexural test, and degree of conversion was analysed with Raman spectroscopy. X-Flow exhibited higher stress values than the other tested materials. Venus Diamond Flow showed the lowest stress values at 40s and at 300s, and the lowest maximum stress rate. Stress values were correlated with elastic modulus but not with degree of conversion, which was comparable among all tested materials

The stretch-activated channel blocker Gd3+ reduces palytoxin toxicity in primary cultures of skeletal muscle cells

Palytoxin (PLTX) is one of the most toxic seafood contaminants ever isolated. Reports of human food-borne poisoning ascribed to PLTX suggest skeletal muscle as a primary target site. Primary cultures of mouse skeletal muscle cells were used to study the relationship between Ca(2+) response triggered by PLTX and the development of myotoxic insult. Ca(2+) imaging experiments revealed that PLTX causes a transitory intracellular Ca(2+) response (transient phase) followed by a slower and more sustained Ca(2+) increase (long-lasting phase). The transient phase is due to Ca(2+) release from intracellular stores and entry through voltage-dependent channels and the Na(+)/Ca(2+) exchanger (reverse mode). The long-lasting phase is due to a massive and prolonged Ca(2+) influx from the extracellular compartment. Sulforhodamine B assay revealed that the long-lasting phase is the one responsible for the toxicity in skeletal muscle cells. Our data analyzed, for the first time, pathways of PLTX-induced Ca(2+) entry and their correlation with PLTX-induced toxicity in skeletal muscle cells. The cellular morphology changes induced by PLTX and the sensitivity to gadolinium suggest a role for stretch-activated channels

Phase Diagrams for Process Design

International audienc

Low emission engine technologies for future tier 3 legislations - options and case studies

Marine emission legislation such as the current IMO Tier II and upcoming IMO Tier III requirements within the revised Marpol Annex VI have been major drivers for performance development of marine engines during the latest years. These requirements have triggered a vast amount of research activity at the engine OEM’s in order to identify and develop the best possible technologies for fulfilling the requirements. A main objective of this research has been to identify the various options available for reducing engine SOx and NOx emissions and to clarify the main criteria engine manufacturers consider to determine the optimum technology. Another objective has been to investigate how ship-owners and operators within the various marine segments are impacted by the new emissions requirements and what key factors they need to consider when identifying the optimum engine technology. Case studies conclude that the optimum solution can vary depending on the vessel application, operating time inside ECAs, as well as prices for fuels and reduction agents. In new-building cases, gas operated engines without after-treatment systems show a strong value proposition as an alternative to liquid fuel engines that require after-treatment solutions - especially for short-haul shipping applications where tighter emission legislations are enforced to a larger extent. Overall, 2-stage turbo charging, LNG, and SCR technologies are concluded to be the most feasible technologies. Generally, lower operating costs can compensate higher capital expenditures meaning that the owner should carefully evaluate the total cost of ownership of the various alternatives, and not consider only the initial capital expenditure. The choice of best technology option depends on a variety of issues which can change over time - such as the operation profile and route of the vessel and commodity prices. Consequently the ship-owner should evaluate the alternative technologies for a wide range of possible scenarios to find a flexible solution that minimizes exposure to risks related to changing boundary conditions. With this research, the reasons why certain emission reduction technologies are preferred to others both from OEM’s and ship-owner’s point of view are quantified and the most feasible technologies for meeting the requirements are identified.fi=vertaisarvioitu|en=peerReviewed