Processing of cellular ceramics by foaming and in situ polymerisation of organic monomers

This paper describes studies on a new processing route for fabricating highly porous ceramics. The method is based on the generation of a foam from an aqueous suspension of ceramic powder and the subsequent stabilisation of the structure by in situ polymerisation of organic monomers. The influence of the slip viscosity on the foam volume and stability was determined using concentrated alumina suspensions containing dispersing agents and two commercial foaming agents. The in situ polymerisation of organic monomers led to fast solidification, resulting in strong, porous bodies which could withstand machining. The resulting ceramic foams consisted of a highly interconnected network of spherical cells with densities as low as 6% of theoretical. The distribution of cell size was dependent both on the density of the specimen produced and on the time for polymerisation onset. The size ranged from approximately 30 to 600 mm. Enlargement of cell size to achieve materials of higher permeability was possible through expansion of the foam via pressure reduction before polymerisation. The creation of highly densified struts between the cells led to flexural strengths as high as 26 MPa

Preferencias hacia carne de cordero en supermercados de Temuco, región de la Araucanía, Chile

Lobos, G (Lobos, German). Univ Talca, Escuela Ingn Comercial, Talca, ChileThe low levels of consumption of lamb meat in Chile suggest the need for studies on consumer preferences in order to orient production. A study with this object was carried out to evaluate preferences for various cuts, breeds, state (fresh or frozen) and price of lamb's meat among supermarket buyers in Temuco, Chile, and the existence of different market segments, through a survey of 400 persons. Using a fractional factorial design for conjoint analysis, it was determined that the state of the meat was more important than the cut, the price and the breed, with a preference for meat in half carcasses and quarters, Araucano lamb, fresh, at a medium price level. Four consumer segments were distinguished by analysis of hierarchic conglomerates. The majority group (47.7%) was sensitive to the state and the cut, with preference for meat in quarters, fresh, Texel breed. The second group (25.3%) was sensitive to the breed, presenting the strongest preferences for meat in whole carcass, fresh, Araucano lamb. The third group (14.3%) was sensitive to the price, preferred meat in quarters, fresh, Araucano lamb. The minority group (12.7%) was sensitive to the state and price, preferring meat in quarters, Texel breed, and was the only group which preferred frozen meat and would pay a higher price. The segments were distinguished by age, ethnic origin and satisfaction with food-related life. Thus the commercialisation strategy for lamb in supermarkets in Temuco should concentrate principally on the sale of fresh meat cut in quarter

Modelling Human Locomotion

This report is a coverage of my 16 weeks practical training at the Center for Sensori-Motor Interaction of the Aalborg University (Denmark). One of their research topics is on the ?eld of the biomedical modelling, where they want to answer the question of the functional behavior of the proprioceptive feedback system of the human body. A valid/good biomedical model could support their hypotheses which are results from different measurements. The original intention of the project was to build a complete walking lower body model to ?nd the reason for proprioceptive feedback during walking. In the middle of the project this original goal was a too high, because of the additional work of redesigning previous work of Huber [26]. The goal is adjusted to design the mechanical and muscle model and a well documented report, so a next project can continue immediately. The mechanical and muscle model appeared to work correct and are veri?ed with measured data. The forward activation of the muscle/mechanical model is not completely the same as expected. This is because the used method does not take co-activation of antagonistic muscle into account. For the continuation of this project a complete measured data set is necessary, because the veri?cation is not 100% valid. This performed veri?cation uses data that is not correlated in the sense that is measured at the same conditions and persons

Corrigendum: Initiating Change of People With Criminal Justice Involvement Through Participation in a Drama Project: An Exploratory Study

Author proofs are not yet ready for revisio

Visual attention modulates the into ration of goal-relevant evidence and not value

When choosing between options, such as food items presented in plain view, people tend to choose the option they spend longer looking at. The prevailing interpretation is that visual attention increases value. However, in previous studies, ‘value’ was coupled to a behavioural goal, since subjects had to choose the item they preferred. This makes it impossible to discern if visual attention has an effect on value, or, instead, if attention modulates the information most relevant for the goal of the decision-maker. Here, we present the results of two independent studies—a perceptual and a value-based task—that allow us to decouple value from goal-relevant information using specific task-framing. Combining psychophysics with computational modelling, we show that, contrary to the current interpretation, attention does not boost value, but instead it modulates goal-relevant information. This work provides a novel and more general mechanism by which attention interacts with choice

Risk assessment of an offshore wind turbine and remaining useful life estimation of the power converter. Improving availability by prioritising failures with higher risk to operation

By 2014, almost 2500 offshore wind turbines were installed in Europe representing 8GW of capacity connected to the grid and, there is a growing market penetration for the next years. Offshore wind farm operators are facing many challenges related to disparate data sources utilisation for O&M logistic optimisation. Therefore, the decision-making process needs to be based on sound analysis of the wind farm information or data available. According to several technical reports operation and maintenance (O&M) cost could reach until 30% of the levelised cost of energy (LCOE). Understanding the reliability of an offshore wind turbine and the resources required to maintain it is crucial to reduce O&M costs and thus, to reduce the levelised cost of energy (LCOE). There is a need to reduce unnecessary tasks, prioritise the most urgent tasks, improve usage of vessels, crew and technicians, reduce the cost of spare parts held and schedule preventative maintenance to minimise downtime and maximise revenue. Currently, risk assessment plays an important role in the operation and maintenance (O&M) strategies of offshore wind farms. A comprehensive failure mode and effect analysis (FMEA) has been carried out to determine critical assemblies of a generic offshore wind turbine with an induction generator, three stages gearbox and monopile foundation. The main objectives of undertaking this comprehensive FMEA was to identify those failures with significant impact on the wind turbine operation and to identify or highlight areas of risk for maintainability and availability. The FMEA is validated with; widely-used data available in the public domain; Lloyd’s Register’s experience of working with wind farm operators and; Lloyd’s Register experience of working on reliability of the mechanical system of different industrial sectors for decades. The FMEA is further augmented and updated by the use of on-going measurements from operating wind farms. Yaw system, pitch system, power converter and gearbox have been identified in the FMEA as the most critical assemblies regarding risk to the turbine operation. Power converter analysis shows high failure rates and a large proportion of undetectable failures, therefore maintenance resources have been spent on fault finding with its corresponding cost. New approaches are necessary to tackle electrical or electronic failures, especially on the power converter. To improve overall reliability, a method to estimate the remaining useful life (RUL) of a fully-rated converter in a variable speed wind turbine is proposed using data commonly available for offshore wind farm operators. Studies show that the economic impact is dominated by failures related to power electronic components such as IGBTs and capacitors due to their higher repair cost. Mathematical models have been developed to correlate turbine operation variables and environmental conditions with failure root causes to define wear and maintenance actions based on the probability of failur