Image analysis applied to engineering geology, a literature review

Image analysis is a technique used in a number of subjects, but to date not extensively used in the geological sciences. The paper describes the way image analysis is used in the various disciplines and presents an overview of the methods and its potential uses in geology and particularly engineering geology. Emphasis is placed on the way image analysis can be applied to rock structures and textures. It is hoped that this overview will provide an introduction to the literature, which is published in a variety of related fields. Electronic Publication     

Investigations for the Validation of the Defect Based Scale Failure Diagrams—Part I: Nickel Oxide

Mechanical stresses imposed on protective oxide scales can lead to cracking and failure of the scale and consequently to a loss of the protective properties. Therefore, an assessment of the mechanical stability limits is of great interest. In this work, a new concept using defect based oxide scale stability diagrams to assess the mechanical stability limits is discussed. In contrast to mechanical failure diagrams proposed earlier, the presented model is based on physical defect size instead of scale thickness. Nickel oxide scales on high purity (99.99 %) nickel were thermally grown in dry and humidified synthetic air to provide a model oxide system. SEM investigations were carried out to examine the physical defect structure in the oxide scales and mechanical 4-point bend testing was used to measure the critical strain for through scale cracking. The data served for establishing a data base for the validation of the defect based scale failure model.     

Application of interrupted cooling experiments to study the mechanism of bainitic ferrite formation in steels

New interrupted cooling experiments have been designed to study the kinetics of bainitic ferrite formation starting from a mixture of austenite and bainitic ferrite. It is found that the kinetics of bainitic ferrite formation during the cooling stage is determined by the isothermal holding time. The formation rate of bainitic ferrite at the beginning of the cooling decreases with increasing prior isothermal holding time. An unexpected stagnant stage during the cooling stage appears when the isothermal holding time increases to a critical point. There are two reasons for the occurrence of the stagnant stage: (i) a solute spike in front of the interface; and (ii) kinetic transition. A so-called Gibbs energy balance approach, in which the dissipation of Gibbs energy due to diffusion inside the interface and interface friction is assumed to be equal to the available chemical driving force, is applied to theoretically explain the stagnant stage. A kinetics transition from a fast growth mode without diffusion of Mn and Si inside the austenite–bainitic ferrite interfaces to a slow growth mode with diffusion inside the interface is predicted. The stagnant stage is caused by the transition to a slow growth mode. The Gibbs energy balance approach describes the experimental observations very well.     

The Minimal Structure and Motion Problems with Missing Data for 1D Retina Vision

In this paper we investigate the structure and motion problem for calibrated one-dimensional projections of a two-dimensional environment. The theory of one-dimensional cameras are useful in several areas, e.g. within robotics, autonomous guided vehicles, projection of lines in ordinary vision and vision of vehicles undergoing so called planar motion. In a previous paper the structure and motion problem for all cases with non-missing data was classified and solved. Our aim is here to classify all structure and motion problems, even those with missing data, and to solve them. In the classification we introduce the notion of a prime problem. A prime problem is a minimal problem that does not contain a minimal problem as a sub-problem. We further show that there are infinitely many such prime problems. We give solutions to four prime problems, and using the duality of Carlsson these can be extended to solutions of seven prime problems. Finally we give some experimental results based on synthetic data.     

Remaining life assessment of welded pipes containing cracks

The presence of flaws, their size and location in the welded region affects the safe service life of pressure pipes operating at elevated temperature. A remaining life assessment was required to determine the probable remaining safe life of pressure pipes in a high-temperature steam distribution system in which crack-like defects had been identified in many welds. The crack-like defects indicated by NDE lacked the required information to fully identify their locations within the pipe wall. The effect of not knowing complete details of the location of the identified cracks was studied by considering a 360° circumferential crack with initial radial dimension a₀. The crack positions evaluated were: an internal surface crack, an external surface crack, and embedded cracks at various distances from the internal wall of the pipe. Crack growth was modeled using time-dependent fracture mechanics and a newly developed computer code.     

Effects of shade nettings,sowing time and storage on baby spinach flavonoids

Flavonoids are important in plant interactions with the environment and may have positive effects on human health. Effects of light quality and quantity on flavonoid concentration were studied in baby spinach (Spinacia oleracea L.) cultivated under three types of shade netting differing in transmittance of UV‐B and PAR, at two times during the season. Leaves harvested at two growth stages for each sowing were subjected to different post‐harvest storage conditions. Shade nettings had a relatively small effect on flavonoid concentration in baby spinach. The largest effect was found when radiation was most intense. The nettings then decreased total flavonoid concentration by 15–24% at the normal commercial growth stage at harvest. Radiation and plant growth both affected flavonoid concentration, in opposite or similar directions depending on time of season. This variation was reflected in the statistical analysis, showing significant interactions among the factors. There were large differences (up to 100%) in flavonoid concentration between the different times of the season, in shaded as well as unshaded spinach. Flavonoid concentration and composition changed during storage, but no consistent difference was found between the shaded and unshaded leaves. In most cases, total flavonoid concentration increased significantly during the first 6 days of storage. In conclusion, the use of shade netting is acceptable for production of baby spinach as regards flavonoid concentration and composition. Copyright © 2007 Society of Chemical Industry     

Effect of Different Packaging Methods on Quality and Shelf Life of Fresh Reindeer Meat

The impact of different packaging methods [vacuum, modified atmosphere packaging (MAP) (60% CO₂ and 40% N₂) and MAP + CO₂ emitter] on the quality of fresh reindeer meat (M. semimembranosus) stored at 4°C for 21 days was investigated. Colour and odour of the meat, drip loss, pH, microbial content, antioxidant capacity and cooking loss were measured. The MAP + CO₂ emitter resulted in prolonged microbial shelf life compared with vacuum and MAP without CO₂ emitter as lower level of total viable counts was detected after 13 and 17 days. Samples stored with CO₂ emitter also had lower drip loss. Samples stored in vacuum had significant lower L*‐value, higher a*‐value and lower intensity of freshness (odour and colour) compared with those stored in MAP and MAP with CO₂ emitter. However, MAP with a gas‐to‐product volume ratio of 1 : 1 seems to be too low in quality preserving. Increased partial pressure by adding a CO₂ emitter improved bacterial inhibition compared with vacuum and traditional MAP. Copyright © 2014 John Wiley & Sons, Ltd.     

In vivo toxicity and biodistribution of intraperitoneal and intravenous poly-l-lysine and poly-l-lysine/poly-l-glutamate in rats

The combination of two differently charged polypeptides, poly-l-lysine (PL) and poly-L-glutamate (PG), has shown excellent postsurgical antiadhesive properties. However, the high molecular, positively charged PL is toxic in high doses, proposed as lysis of red blood cells. This study aims to elucidate the in vivo toxicity and biodistribution of PL and complex bound PLPG comparing intravenous and intraperitoneal administration. Fifty-six Sprague–Dawley rats were used in a model with repeated blood samples within 30 min examining blood gases and blood smears. Similarly, FITC labelled PL were used to track bio distribution and clearance of PL, given as single dose and complex bound to PG after intravenous and intraperitoneal administration. Tissue for histology and immunohistochemistry was collected. Blood gases and blood smears as well as histology points to a toxic effect of high dose PL given intravenously but not after intraperitoneal administration. The toxic effect is exerted through endothelial disruption and subsequent bleeding in the lungs, provoking sanguineous lung edema. FITC-labelled PL experiments reveal a rapid clearance with differences between routes and complex binding. This study advocates a new theory of the toxic effects in vivo of high molecular PL. PLPG complex is safe to use as antiadhesive prevention based on this toxicity study given that PL is always intraperitoneally administered in combination with PG and that the dose is adequate.     

Strategies for revealing deformation and wear mechanisms of polymer composites by combining scanning electron microscopy,energy dispersive x-ray spectroscopy and cross-section techniques—Exemplified by glass fiber reinforced poly-phenylene-sulphide

Polymers and polymer composites are frequently used in tribological applications. However, their use is often limited by excessive wear or plastic deformation, therefore research and development aiming to improve the materials is ongoing. Tribological evaluations of polymer composites often study the friction coefficient and wear rate for different types, sizes and amounts of fillers. But rarely are any mechanisms presented. Although polymer materials differ from metals, the techniques typically used for metal components, for example, scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS), can be adapted to polymer materials, to achieve more informative SEM micrographs and EDS analyses. The aim of this article is to present useful analysis strategies, from sample preparation and selection of viewing angles, to selection of instrument settings and detector types. The strategies are exemplified by analysis of poly-phenylene-sulphide filled with glass fiber, evaluated against steel in a reciprocating ball-on-flat test set-up. This article takes its starting point with the worn surfaces, and subsequently analyze them using SEM and EDS. A selection of cross section preparation techniques, analysis parameters and microscopy settings are presented and discussed. By combining these techniques and settings, the observation of a strongly modified surface layer, as well as sub-surface plastic deformation and imbedded wear particles, is facilitated.