Buckling and strength analysis of panels with discrete stiffness tailoring

Continuous variation of stiffness across flat plates has been shown, theoretically, to improve buckling performance by up to 60%. However, steered fibre manufacturing methods cannot achieve the minimum radius of curvature required for improvement whilst maintaining a high deposition rate. An alternative concept, Discrete Stiffness Tailoring (DST), which varies stiffness within a ply through discrete changes of angle, is compatible with high rate deposition methods such as Advanced Tape Laying. Through the simple example of redistribution of the material in a quasi-isotropic [±45/90/0]2S laminate whilst maintaining ply percentages, DST is shown both experimentally and theoretically to improve buckling stress by at least 15% with no indication of failure in regions of discrete angle change (seams). However, the reduced tensile strength of seams obtained by virtual and experimental testing means that increased buckling performance in the principle load direction needs to be balanced against loss of transverse strengthThis work was supported by the UK EPSRC ADAPT research project (grant number EP/N024508/1) which is gratefully acknowledged. Richard Butler is supported by a Royal Academy of Engineering and GKN Aerospace Research Chair. Lucie Culliford’s PhD studentship is 50% funded by GKN Aerospace

Sequential Monte Carlo with transformations

This paper examines methodology for performing Bayesian inference sequentially on a sequence of posteriors on spaces of different dimensions. For this, we use sequential Monte Carlo samplers, introducing the innovation of using deterministic transformations to move particles effectively between target distributions with different dimensions. This approach, combined with adaptive methods, yields an extremely flexible and general algorithm for Bayesian model comparison that is suitable for use in applications where the acceptance rate in reversible jump Markov chain Monte Carlo is low. We use this approach on model comparison for mixture models, and for inferring coalescent trees sequentially, as data arrives

Sequential Monte Carlo with transformations.

This paper examines methodology for performing Bayesian inference sequentially on a sequence of posteriors on spaces of different dimensions. For this, we use sequential Monte Carlo samplers, introducing the innovation of using deterministic transformations to move particles effectively between target distributions with different dimensions. This approach, combined with adaptive methods, yields an extremely flexible and general algorithm for Bayesian model comparison that is suitable for use in applications where the acceptance rate in reversible jump Markov chain Monte Carlo is low. We use this approach on model comparison for mixture models, and for inferring coalescent trees sequentially, as data arrives

Characterisation, potential toxicity and fate of storm water run-off from log storage areas of the Port of Tauranga.

Stormwater run-off from industrial sources can impact the receiving environment by the discharge of toxic substances, nutrients, sediments or fresh water (in marine environments). The Port of Tauranga is New Zealand’s largest by cargo volume with untreated logs being one of the major exports. The port stores logs totalling up to 300,000 m3 with an average residency time of 18 days. Runoff from log storage areas can cause toxicity to aquatic life due to low pH, high organic solids content and associated BOD, and chemicals leached from timber such as resin acids. Metals and PAH’s from heavy vehicles and other machinery can also be present. At the port, stormwater collects from the storage areas into slot drains and is screened for larger particulates in screening chambers before discharging into Tauranga Harbour. Large rainfall events produce a visible, highly coloured plume extending across the main harbour channel. This study looks at compounds within the stormwater runoff and associated marine water samples and the toxicology of the effluent. It then focusses on the gradients of compounds found in sediments and biota in relation to the main discharge sources. This is followed with a more specific investigation of the bioaccumulation of resin acids in resident and transplanted mussels. It concludes with a comparison of low intertidal species assemblages within and outside the influence of the stormwater plume. Findings indicate that there are high levels of wood derived chemicals in the stormwater runoff and a gradient of quantities of these can be detected in nearby sediments, decreasing with distance from the discharge point of the effluent. Those compounds, such as metals, able to be quantified against national and international guidelines were well within acceptable levels. Others, such as resin acids, were found in lower quantities than in a previous study. A correlation between organics related to leachate from the logs, inorganic compounds found in the effluent and sediment grain size, indicates that some elements of the runoff may reach further into the harbour. The influence of dredging and disturbance of the seabed by shipping movements is considered in relation to this. Levels of organic compounds, related to the log storage in transplanted mussel populations, were not detected spatially or temporally and no evidence of bio-accumulation of resin acids was found. Based on the combined findings there are very low detectable effects on the marine environment from the runoff of the Port of Tauranga log storage areas. These come in the form of a gradient in chemical compounds related to the runoff and are well within the ANZECC (2000) Interim Guideline Levels. This study adds to the limited knowledge on log storage runoff into the marine environment and incorporates elements which can be applied to many areas of research related to stormwater discharge. It uses the Port of Tauranga runoff as a relevant example of issues and environmental responses related to urban and industrial stormwater runoff

Planar Chiral Ferrocene Lithium Amide Bases: A New Generation of Bases for Asymmetric Synthesis

The design and preparation of a new class of planar chiral ferrocenyl lithium amide bases is described. Work commenced on preparing N./V-dimethyl-l-ferrocenylethylamine derivatives. Electrophilic amination was attempted with a variety of reagents, but no diamines were ever obtained. The introduction of a boronic acid group was also attempted, but no products were isolated. Finally, nitration followed by reduction was investigated, but again proved unsuccessful, resulting only in the preparation of a dimer of the starting amine, 2,2'-bis-[ 1 -(//, A-dimethylamino)-ethyl]-l, l'-biferrocenyl. Our attention turned to derivatives of MN-diisopropylferrocene carboxamide. Metallation, followed by quenching with iodine gave Af,N-diisopropyl-2- iodoferrocene carboxamide. Copper(I) oxide mediated coupling of the iodide with either acetic acid or phthalimide gave access to ortho-oxygen and nitrogen donor groups. A new class of planar chiral bases (N-alkyl-(2- alkoxyferrocenyl)methylamines) were prepared from this starting material by reduction of the amide, followed by substitution of the diisopropylamine with a range of primary amines. Assays were carried out using the deprotonation of 4-tert-butylcyclohexanone and trapping of resultant enolate with TMSC1. Bases having a plane of chirality as the only stereochemical element, disappointingly, gave nearly racemic silyl enol ether, however low optical purities were recorded for bases consisting of both central and planar chirality. A non-chelating planar chiral lithium amide base was prepared (^S}-A^-rer/-butyl-(2-methylfen'ocenyl)-t methylamine, however this too gave nearly racemic silyl enol ether in the assay reaction. The synthesis of planar chiral azaferrocenyl bases was attempted by sequential complexation of lithiated pyrrole-2-methanol and lithium pentamethyl- cyclopentadienide with iron(II) chloride, followed by acylation of the pendant alcohol. However, all attempts to substitute the acetate with an amine proved unsuccessful