Search

Increasingly stringent equipment performance and reliability requirements are being specified to the aerospace industry by aircraft manufacturers, driven by the expectations of both certification authorities and operators. The reality is that aircraft system and equipment reliability in service can fail to meet the design expectations. This thesis details the problem areas within the current analysis process, describing the procedures currently in use and showing what can go wrong. It goes on to propose action that can be taken to ensure safety levels are maintained and details a new approach that is unique to this thesis. The author has devised a new System Safety Compliance Model (SSCM) for ensuring that aircraft system safety standards can be better maintained. Evolved from his earlier highly successful database system at TRW Lucas Aerospace, SSCM will be: - Demonstrably cost effective - A step change in process capability, offering "something new" - Instantly accessible at shop floor level to everyone in the business - Easy to use and as automated as possible to minimise staff training requirement - Capable of performing instant re-assessment of safety performance down to system level and including consideration of a variety of operating environments and conditions - The industry standard repository of component reliability data - "Centrally" owned by a world-wide recognised industry body SSCM is the first system to operate in such a way, and will ensure that the original system safety analysis performed at the design stage, is continually assessed for accuracy throughout its in-service life. If the new methods detailed in this thesis are adopted and acted upon, there is a high probability of a reduction in the risk of aircraft systematic failure in service, leading to increased safety in aviation. The model can be equally applied to other areas of transportations uch as railways.

Increases of temperature in the range from 8 to 18°C in vivo, significantly enhanced the dry weights of lateral rhizomes, roots and shoots. At the higher temperatures dry weight production was often seen to decrease. Decreases in irradiance from 100 to 50 per cent in vivo, produced significant decreases in the dry weights of lateral rhizomes, roots and shoots. In contrast, the numbers of lateral rhizomes, tubers and shoots were largely unaffected by temperature and irradiance treatments. Day length treatments of 8 to 16 hours light in a 24 hour period in vivo produced few significant changes in either the dry weights or numbers of plant parts produced. However, day length had a strong influence over the time of flowering. For maximum rhizome production a temperature of between 13 and 18°C, a high irradiance and a short day length were required. Increases of temperature in the range 8 to 18°C in vitro, caused significant increases in the number of lateral rhizomes and shoots produced. At the highest temperature the numbers produced often decreased. The number of roots produced was unaffected by temperature. Decreases in irradiance from 100 to 25 per cent and increases in day length from 8 to 20 hours light in a 24 hour period, produced no significant changes in the number of lateral rhizomes, roots or shoots produced in vitro. Low irradiance, however, caused etiolation of the shoots. For a good multiplication rate the requirements for the culture environment were a temperature of 15°C, an irradiance of 5 Win- 2 with a day length of 8 hours of light in a 24 hour period. The presence or absence of tubers and damage suffered by `splits' prior to planting were found to be important factors in the establishment of plants in vivo. Subculture of rhizome explants without aerial shoot or rhizome apices and of rhizome explants divided into single internodes with or without aerial shoots, enhanced the rhizome multiplication rate. Addition of the plant growth regulators triiodobenzoic acid, thidiazuron, α-naphthaleneacetic acid, gibberellic acid and paclobutrazol to culture media, with and without BAP, caused no significant changes in the numbers of lateral rhizomes, shoots or roots produced. However, paclobutrazol produced changes in explant morphology, i.e. shoot size was reduced and the diameter of roots was increased.

This study is an assessment of the effect of plants, vesicular arbuscular mycorrhizal fungi (VAM), and seasonality on Bioretention Cell performance. Performance was evaluated as retention of nitrate, ammonium, and phosphate during foliaged and dormant seasons. This study is intended to evaluate the significance of plant presence and VAM interaction in laboratory-scale Bioretention Cells by quantifying changes in effluent volume and nutrient concentration and load following two-liter applications of a synthetic stormwater (SSW) containing 2mg/L nitrate, ammonium, and phosphate (as N and P). Bioretention Cells were leached with deionized water (DI) for 33-weeks to bring leachate concentration below SSW levels. In week thirty-four SSW was added weekly for three weeks to each Bioretention cell while plants were dormant (12_Jan_08 through 2_Feb_08) and while plants were foliaged (19_Apr_08 through 10_May_08). Plants have a significant role in the process of bioretention. Vesicular arbuscular mycorrhizal fungi where not initially present in the roots of plants used for this study and failed to colonize the roots of these plants during this experiment, VAM was not significant in any of the results. Bioretention Cells with dormant and foliaged plants infiltrated and released effluent significantly faster than Bioretention Cells without plants. Foliaged plants significantly reduced total effluent volume. Very little ammonium was released by any Bioretention Cell, with or without plants. Dormant plants reduced effluent concentration and load of nitrates and phosphates relative to the SSW, but foliaged plants only reduced phosphates. Bioretention cells with foliaged plants increased nitrate concentration relative to SSW, but still significantly below that of Bioretention Cells without plants. Plants significantly influence infiltration rates, effluent concentration and loading of nitrates, phosphates, and ammonium; seasonality (plant dormancy/foliaged) significantly influences these results.