From Samples to Complex Objects: Detecting Material Degradation in Plastic Artworks

The prevalence of polymers in our daily lives has slowly begun to be reflected within the collections of various museums. The realisation that not all plastic objects are as stable as more traditional materials – such as metal or stone – has ushered in a host of new challenges. Central to understanding the broader issues relating to ‘modern polymeric materials’ is the ability to identify their base polymer and monitor their degradation. By exploiting the natural phenomena by which plastic objects emit volatile organic compounds (VOCs), this thesis aimed to investigate the use of VOCs, via solid phase microextraction (SPME) gas chromatography mass spectrometry (GC/MS), to monitor the degradation of art and design objects made in part or exclusively from plastics. This project highlighted the binary nature of SPME analysis – one the one hand the methodology is able to detect identification and degradation markers emitted from an object with ease. On the other, tracking those markers over long time periods is extremely difficult. The project noted a number of influencing factors to the resulting VOC profile with fluctuations in temperature seen to cause the greatest difficulty. Experiments investigating temperature’s role showed that VOC emissions were depressed when analysed at lower temperatures, however, no consistency was found between either the different samples or the different VOCs examined. Therefore, no conversion factor can be applied to either sample or VOC in order to account for a change in temperature. Principal component analysis (PCA) highlighted the importance of examining a VOC profile emitted from an object rather than relying on a single VOC. Through the use of PCA it was possible to distinguish many of the different temperature and aging combinations

Comparison of selected reduced-tillage planting systems in cotton and soybeans

Performances of five commercially available no-tillage and reduced-tillage planting systems were evaluated for cotton and soybean production at the Milan Experiment Station in Gibson County, Tennessee. Evaluations were based upon consistency of seed placement, ability to produce a viable stand, soil moisture preservation, and crop yield. Seed placement data were collected from randomly selected row segments seeded with each planter. Seeds were excavated and coefficients of variation were determined for both seed depth and spacing. Stand counts, canopy measurements and relative root length determinations were taken during several stages of plant growth. Stand and canopy dimensions varied at times due to planting system, and in some cases root growth also differed by row spacing and sampling depth. Soil cores were extracted on 18 August 1987 for soil moisture and plant root length determination. These cores were taken both directly in the drill and in the row middles to a depth of 90 centimeters in 15-centimeter depth increments. Tillage treatment, and on several occasions row spacing, were found to significantly effect both soil moisture and relative root length. A combine was used to harvest soybeans. Cotton plots were stripper harvested since row spacing was less than that required for conventional picker harvesting. Planting system had no significant effect on yields of either soybean or cotton

Managing power amongst a group of networked embedded fpgas using dynamic reconfiguration and task migration

Small unpiloted aircraft (UAVs) each have limited power budgets. If a group (swarm) of small UAVs is organized to perform a common task such as geo-location then it is possible to share the total power across the group by introducing task mobility inside the group supported by an ad hoc wireless network (where the communication encoding/decodeing is also done on fpgas). In this presentation I will describe research into the construction of a distributed operating system where partial dynamic reconfiguration and network mobility are combined so that fpga tasks can be moved to make the best use of the total power available in a swarm of UAVs

Outperformance in exchange traded fund pricing deviations: generalised control of data snooping bias

An investigation into Exchange Traded Fund (ETF) outperformance during the period 2008-2012 is undertaken utilising a data set of 288 US traded securities. ETFs are tested for Net Asset Value (NAV) premium, underlying index and market benchmark outperformance, with Sharpe, Treynor and Sortino ratios employed as risk adjusted performance measures. A key contribution is the application of an innovative generalised stepdown procedure in controlling for data snooping bias. It is found that a large proportion of optimized replication and debt asset class ETFs display risk adjusted premiums with energy and precious metals focused funds outperforming the S&P500 market benchmark

Oil Market Modelling: A Comparative Analysis of Fundamental and Latent Factor Approaches

International audienceWe formally compare fundamental factor and latent factor approaches to oil price modelling. Fundamental modelling has a long history in seeking to understand oil price movements, while latent factor modelling has a more recent and limited history, but has gained popularity in other financial markets. The two approaches, though competing, have not formally been compared as to effectiveness. For a range of short-medium-and long-dated WTI oil futures we test a recently proposed five-factor fundamental model and a Principal Component Analysis latent factor model. Our findings demonstrate that there is no discernible difference between the two techniques in a dynamic setting. We conclude that this infers some advantages in adopting the latent factor approach due to the difficulty in determining a well specified fundamental model

Collective responsibility and mutual coercion in IoT botnets: a tragedy of the commons problem

In recent years, several cases of DDoS attacks using IoT botnets have been reported, including the largest DDoS known, caused by the malware Mirai in 2016. The infection of the IoT devices could have been prevented with basic security hygiene, but as the actors responsible to apply these preventative measures are not the main target but just “enablers” of the attack their incentive is little. In most cases they will even be unaware of the situation. Internet, as a common and shared space allows also some costs to be absorbed by the community rather than being a direct consequence suffered by those that behave insecurely. This paper analyses the long term effects of the prevalence of a system where individual decision-making systematically causes net harm. An analogy with “the tragedy of the commons” problem is done under the understanding that rational individuals seek the maximization of their own utility, even when this damages shared resources. Four areas of solution are proposed based on the review of this problem in different contexts. It was found necessary to include non-technical solutions and consider human behaviour. This opens a discussion about a multidisciplinary focus in IoT cyber security

On-farm Cooperator Trials 2011: Effect of Extended-duration Row Covers on Muskmelon and Winter Squash on Bacterial Wilt and Yield

Susceptible cucurbit crops are difficult to grow in Iowa because of bacterial wilt, caused by Erwinia tracheiphila. Striped and spotted cucumber beetles transmit bacterial wilt. Other insect pests such as squash vine borer and squash bugs may also have an economic impact on yield, particularly in squash