Implementing Rapid Prototyping Using CNC Machining (CNC-RP) Through a CAD/CAM Interface

This paper presents the methodology and implementation of a rapid machining system using a CAD/CAM interface. Rapid Prototyping using CNC Machining (CNC-RP) is a method that has been developed which enables automatic generation of process plans for a machined component. The challenge with CNC-RP is not the technical problems of material removal, but with all of the required setup, fixture and toolpath planning, which has previously required a skilled machinist. Through the use of advanced geometric algorithms, we have implemented an interface with a CAD/CAM system that allows true automatic NC code generation directly from a CAD model with no human interaction; a capability necessary for a practical rapid prototyping system.Mechanical Engineerin

Level repulsion in hybrid photonic-plasmonic microresonators for enhanced biodetection

We theoretically analyse photonic-plasmonic coupling between a high Q whispering gallery mode (WGM) resonator and a core-shell nanoparticle. Blue and red shifts of WGM resonances are shown to arise from crossing of the photonic and plasmonic modes. Level repulsion in the hybrid system is further seen to enable sensitivity enhancements in WGM sensors: maximal when the two resonators are detuned by half the plasmon linewidth. Approximate bounds are given to quantify possible enhancements. Criteria for reactive vs. resistive coupling are also established

Electricity Generation in Fiji: Assessing the Impact of Renewable Technologies on Costs and Financial Risk

In recent years, renewable energy technologies have been advocated in Fiji on the basis that they improve energy security and serve as a risk-mitigation measure against oil price volatility. Despite this, there have been few attempts to measure the impact of renewable technologies on energy security. That analysis is important if the benefits of renewable energy technologies in Fiji are to be adequately evaluated. This paper develops and applies a method for assessing the potential contribution of renewable technologies to the security of electricity supply in Fiji. The method is based on an application of portfolio theory, traditionally used in financial markets, to the electricity generation mix in Fiji. The results demonstrate the impact of different renewable technologies on both portfolio generation cost and risk for Fijian electricity grids.renewable energy technologies, energy policy, electricity sector, Fiji, oil prices, portfolio analysis, Pacific islands, Resource /Energy Economics and Policy,

Signalling mechanisms of long term facilitation of breathing with intermittent hypoxia.

Intermittent hypoxia causes long-term facilitation (LTF) of respiratory motor nerve activity and ventilation, which manifests as a persistent increase over the normoxic baseline for an hour or more after the acute hypoxic ventilatory response. LTF is likely involved in sleep apnea, but its exact role is uncertain. Previously, LTF was defined as a serotonergic mechanism, but new evidence shows that multiple signaling pathways can elicit LTF. This raises new questions about the interactions between signaling pathways in different time domains of the hypoxic ventilatory response, which can no longer be defined simply in terms of neurochemical mechanisms

Computing Axes of Rotation for Setup Planning Using Visibility of Polyhedral Computer-Aided Design Models

This paper presents a method for determining feasible axes of rotation for setup planning, based on the visibility of a polyhedral model. The intent of this work was to develop a feature-free approach to setup planning, with the specific focus on multi-axis machine setups. Visibility mapping can provide a quantitative evaluation of a surface, a feature or an entire part model; however, the next step is to use this information for process planning. In this paper, we present an approach of using a visibility map to evaluate axes of rotation that could be used in an indexer-type setup on a machine tool. Instead of using expensive and complicated multi-axis machining, it may be feasible to machine using multiple three-axis toolpaths if a single axis of rotation can be used to rotate the part through the minimum set of orientations. An algorithm is presented that is capable of processing visibility information from a polyhedral model; hence, the method is generic and does not require feature detection. As such, the work is applicable to a variety of applications; in particular for subtractive rapid prototyping where complex geometry may not contain recognizable features