Linde (United Kingdom)

The extensive Computational Fluid Dynamics (CFD) modelling of cooling using nitrogen jets showed that an optimised array of high-velocity gas jets close to its surface could cool the part at a speed similar to that of oil. When these optimised conditions were applied to an idealised gear form, the model suggested that it could be fully hardened if a nitrogen/hydrogen mixture was used. Physical experiments under exactly the same conditions were carried out to try and validate the model. Unfortunately, although close to the physical results, the model results had some important differences. When the model was modified to correct radiation and dynamic-specific heat effects, there was a closer, but by no means perfect, agreement. The finite-element model used at this stage was thought to model heat transfer accurately, but not steel. Therefore, the heat transfer data were applied to a metallurgical model. The results from this model were superior in some respects, particularly regarding the occurrence of phase changes, although it is - again - not perfect.

There are theoretical benefits of delivering drug aerosols to patients with asthma and chronic obstructive pulmonary disease (COPD) using Heliox as a carrier gas. The objective of this study was to develop systems to allow bronchodilators nebulized by a breath enhanced jet nebulizer and a vibrating mesh nebulizer to be delivered to patients in Heliox. This was achieved by attaching a reservoir to the nebulizers to ensure inhaled Heliox was not diluted by entrained air. For the vibrating mesh nebulizer, the total output was significantly higher after 5 min of nebulization when Heliox rather than air was used as the delivery gas (p < 0.001). The proportion of drug in particles <5 microm was 58.1% for Heliox and 50.1% when air was entrained. When the breath enhanced nebulizer was used a much higher driving flow of Heliox, compared to air, was required to deliver a similar dose of drug (p < 0.05). The total amount of drug likely to be inhaled was significantly higher when the vibrating mesh nebulizer (Aerogen) was used compared to the breath enhanced jet nebulizer (Pari LC plus) (p < 0.001). The amount of drug likely to be inhaled was also significantly greater for the adult as opposed to pediatric breathing pattern for all nebulizers and flows tested with the exception of the Aeroneb and Heliox entrainment. In this case, total amounts were similar for both patterns but for the pediatric pattern, the time taken to reach this output was longer. Such information is required to allow appropriate interpretation of clinical trials of drug delivery using Heliox.

Dynamic programming gives a new method for computing the wave function in quantum mechanics. The paper compares this method with Feynman's path integral method (1965).