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Active anti-corrosion pigments, such as strontium chromate, are essential components of many corrosion protective organic coatings, since these leach out to provide active inhibition to the metallic substrate at the defective areas of the coatings arising during service from mechanical and/or environmental damages. Currently, formulators use empirical tests to determine effective inhibitor concentration, because the factors that determine leaching behaviour are poorly understood. In this study, we present insights into leaching mechanisms by correlating the microstructure of model coatings pigmented with strontium aluminium polyphosphate hydrate (SAPH) to the transport of different species. It is found that diffusion and transport of active species through the polymeric matrix does not significantly contribute to the leaching kinetics. Thus, leaching starts when inhibitor pigments are in direct contact with the environment via surface-breaking defects in the coating, and continues as long as the cluster of connected inhibitor pigments is in direct contact with the environment, until 3-dimensional connectivity is lost. Therefore, the extent, shape and size of the clusters of connected inhibitor pigments, as well as the solubility and dissolution rates of individual pigments, play important roles in the leaching process. Additionally, the 3-dimensional percolation threshold (Pc) for pigment connectivity is proposed as a critical parameter that has significant influence on the leaching rate as well as the barrier properties of corrosion protective coatings.

The uncertainties of renewable energy may bring impacts to power system reliability. This paper proposes a novel generation rescheduling algorithm, which adjusts generation outputs to mitigate the variations of branch power flows and relieve the overload probability. This algorithm helps prevent power congestion and balance the aggregate renewable generations and loads in power systems. Besides, the paper also proposes a probabilistic method evaluating the system uncertainty issue in the power system considering generation rescheduling operation. The proposed generation rescheduling algorithm has been tested on the Arizona transmission system. The generation rescheduling method enhances power system reliability analysis with a high penetration of renewable energy resources.

An experimental protocol (workflow) has been developed for time-lapse x-ray nanotomography (nano-CT) imaging of environmentally driven morphological changes to materials. Two case studies are presented. First, the leaching of nanoparticle corrosion inhibitor pigment from a polymer coating was followed over 14 days, while in the second case the corrosion damage to an AA2099 aluminium alloy was imaged over 12 hours. The protocol includes several novel aspects relevant to nano-CT with the use of a combination of x-ray absorption and phase contrast data to provide enhanced morphological and composition information, and hence reveal the best information to provide new insights into the changes of different phases over time. For the pigmented polymer coating containing nominally strontium aluminium polyphosphate, the strontium-rich components within the materials are observed to leach extensively whereas the aluminium-rich components are more resistant to dissolution. In the case of AA2099 it is found that the initial grain boundary corrosion is driven by the presence of copper-rich phases and is then followed by the corrosion of grains of specific orientation.

An organic primer pigmented with strontium aluminium polyphosphate for the corrosion protection of zinc alloy coated steel was investigated by electron microscopy and electrochemical impedance spectroscopy after exposure to sodium chloride solution. The development of defects within the organic coating was found to be related to the solubility of the pigment, which resulted in two conflicting effects. On the one hand, the inhibitive species released from the solid pigment reduced the corrosion rate of the metal substrate by formation of precipitated products containing zinc, strontium, aluminium, phosphorus and oxygen. On the other hand, the dissolution of the inhibitive pigment resulted in porosity in the coating that created easy pathways not only for the inhibitors to reach the substrate but also for the aggressive species to migrate inwards to the metal surface and, importantly, for the transport of corrosion products outwards.

The protective film formed in a defect by leaching of lithium oxalate from model organic coatings during neutral salt spray exposure has been investigated. A scribed area of about 1 mm width was introduced on the coated AA2024-T3 aluminium alloy. The scribed area was examined before and after exposure in neutral salt spray environment for 4, 8, 24 and 168 h by scanning and transmission electron microscopies. It was found that the lithium oxalate was able to leach from the organic coating during neutral salt spray exposure and it promoted the formation of a film that provided effective corrosion protection to the alloy. The typical film morphology consists of three different layers, including a relatively compact layer near the alloy substrate, a porous middle layer and a columnar outer layer. Variation of the film morphology was also observed at different locations of the scribed alloy surface, which may be related to the difference of local concentration of lithium species. Electron energy loss spectroscopy detected lithium, aluminium and oxygen in the film. Although the film showed the varied morphologies in different regions of the scribed area, the alloy substrate was protected from corrosion when the film was formed. Copyright © 2016 John Wiley & Sons, Ltd.

This paper describes the application of finite element (FE) analysis to the prediction of the non-linear elasto-plastic collapse of ring-stiffened cylinders under hydrostatic loading. A range of legacy experimental test models have been analysed using FE idealisations generated using measured as-built shape data including out-of-circularity (OOC), frame alignment and tilt and other scantlings. The FE models also explicitly included the residual stresses caused by cold bending. Short and long ring-stiffened cylinders, which were designed to isolate interframe and overall collapse modes, respectively, were considered as were some intermediate length cylinders where the possibility of interactive collapse was also present. In general, the collapse pressures were predicted to within 6%. However, for some of the interframe collapse models, it was necessary to use the minimum measured plate thickness to achieve this. This was largely attributable to the limited measured plate thickness data.

Siemens Medical Solutions, Oncology Care Systems Group (SMSOCSG) is supporting the development of several technologies that enable image acquisition and decision making processes required for IGRT in various clinical settings. Four such technologies are presented including: (i) the integration of a traditional multi-slice computed tomography (CT) scanner “on rails” with a C-arm gantry linear accelerator; (ii) the development of a high sensitivity, fast, megavoltage (MV) electronic portal imaging device capable of clinical MV Conebeam CT (MVCBCT) reconstruction and fluoroscopy mounted on a C-arm gantry linear accelerator; (iii) the modification of a mobile C-arm with flat panel kilovoltage (kV) diagnostic imager; and (iv) the development of an in-line megavoltage and kilovoltage flat panel imaging system that has the potential to image both anatomical and dosimetric information in “real-time” utilizing the traditional C-arm gantry linear accelerator geometry. Each method of IGRT has unique as well as complementary qualities which are discussed from both a clinical and technical perspective.

Coil-coated zinc-alloy steel is a widely used commodity from white-goods manufacture to architectural claddings. Corrosion protection is generally provided to the substrate, and to any exposed cut edges, by a primer coating using an inhibitive pigme that, conventionally, consists of strontium chromate. However, chromate-free formulations containing phosphate-type pigments are now preferred. A common primer formulation contains strontium aluminium polyphosphate (SAPP) and, in previous work, it has been determined that the solubility of such inhibitors has two conflicting effects. On the one hand, free ions released from the inhibitor migrate to the metal substrate and reduce/inhibit corrosion by formation of a thin precipitated salt film containing zinc, phosphorous and oxygen. On the other hand, the dissolution of the inhibitor results in an increased porosity in the coatings, consequently creating more obvious pathways for aggressive species to reach the metal surface and for the transport of corrosion products. Further, insoluble corrosion products, or precipitated inhibitive salt films, in some cases appear to fill the cavities left by the dissolution of the SAPP inhibitor and, consequently, provide potentially improved barrier protection to the metal substrate. In the present study the leaching behaviour of nano- to micron scale corrosion inhibitor pigment, of strontium aluminium polyphosphate from a polymer coating was followed over 14 days by 4D x-ray nano tomography. It is apparent that SAPP is not a homogeneous material and contains both strontium-rich components, which leach extensively, and aluminium-rich components, which are more resistant to dissolution. Through the investigation of individual pigment particles and their 3D spatial connections in the polymer matrix, the transport routes of the leaching particles in the polymer matrix may be explored. The figure shows the evolution of an organic coating pigmented with SAPP corrosion inhibitor over the course of immersion in sodium chloride solution: (a) before immersion; (b) after immersion for 1 day; (c) after immersion for 7 days; (d) after immersion for 14 days. The oval regions highlight the dissolution of strontium-rich particles while the square region highlight the aluminium-rich components of the SAP. Figure 1

DRA Dunfermline has had a continuing involvement in the development of deep diving composite pressure hulls through the NERC Autosub project and as part of the MAST II programme which culminated recently in the testing of a relatively large scale model pressure hull. This paper describes analytical models which were developed in conjunction with a series of model tests and used in the design of the large scale hull model. Comparisons between theoretical predictions and experimental data are also given. In keeping with the topic of the workshop the emphasis is on buckling with stress and failure analysis being reported more fully elsewhere.

Strontium aluminium polyphosphate (SAPP) inhibitive pigment formulated into an organic primer for corrosion protection of zinc alloy coated steel in 0.6 M sodium chloride solution was investigated by serial block face imaging using scanning electron microscopy, which provided detailed information on inhibitor releasing, transportation and reaction with zinc alloy substrate. It was found that SAPP contains at least two distinct particle types, one which is strontium rich and another which is aluminium rich. These particles have different release characteristics which are dependent on the local environment. The strontium rich particles release their components faster in near neutral and acidic environment compared with the aluminium rich particles whilst in an alkaline environment the reverse is found. The pH related inhibitor release process and the mixture of the inhibitive pigment with different strontium to aluminium ratios ensure the availability of the inhibitor at both anodic and cathodic locations, which consequently reduced/retarded the corrosion of zinc alloy coated steel.

DRA Dunfermline first became involved in the development of a composite pressure hull for a deep ocean submersible with the NERC Autosub project and this work has continued under the European MAST II programme. This paper describes the analysis which has been carried out in support of an extensive programme of model testing. An anisotropic Lame solution has been developed for the analysis of cylindrical components under external pressure and this was used to evaluate some of the popular failure criteria. Extensive use was also made of the Finite Element method.

There are many sources of failure within a System-on-Chip (SoC), so it is important to look beyond the processor core at other components that affect the reliable operation of the SoC, such as the fabric included in every one that connects the IP together. We use ARM's AMBA 3 AXI bus matrix to demonstrate that the impact of errors on the IP interconnect can be severe: possibly causing deadlock or memory corruption. We consider the detection of 1-bit transient faults without changing the IP that connects to the bus matrix or the AMBA 3 standard and without adding extra latency while keeping the performance and area overhead low. We explore what can be done under these constraints and propose a combination of techniques for a low-tech solution to detect these rare events.

Fig. 2. Anteroposterior Tc-MDP bone scan of pelvis indicates foci of increased uptake of radiopharmaceutical at the left femoral neck and right iliac wing of pelvis Fig. 3. A Spin echo T1 weighted (TR 70, TE 17) coronal sections of pelvis demonstrate the presence of low-signal deposits in both the neck of the left femur and the iliac wing on the right side. B Gradient echo (flip angle 40 ~ ) FISP sequences demonstrating an area of high signal in the neck of the left femur and the iliac wing on the right side Clinical information

Fig. I. Left hip radiograph demonstrating the presence of a pathological fracture through the femoral neck Fig. 2. Left hip radiograph 8 weeks following the placement of a femoral head Charnley prosthesis, demonstrating the presence of gross swelling of the soft tissues of the thigh Fig. 3. Axial contrast-enhanced computed tomogram of the upper shafts of both femora. Despite the presence of prosthesis-induced metal artefact, gross circumferential swelling of the soft tissues of the upper left thigh is clearly identifiable, associated with thickening of subcutaneous soft tissue strands Clinical information

Conductive copper lines were directly written on paper through inkjet printing of a copper salt and a reducing agent sequentially from a multi-color printhead. The copper ink was an aqueous copper citrate solution and the reducing agent was a solution of sodium borohydride (NaBH4). The two inks were loaded in two separate compartments of a traditional HP color cartridge, which enabled the generation of two droplet streams from the two separate compartments. The cartridge was fixed above an X–Y positioning table and conductive copper lines were prepared using multiple printing passes. The estimated conductivity obtained on paper (1.8 × 106 S m−1) is about 1/30 that of bulk metal copper (59.6 × 106 S m−1 at room temperature). Oxidation of the printed copper lines was studied using EDS elemental analysis of lines printed onto poly(vinylidenefluoride), PVDF, membranes. The Cu–O ratio of copper lines decreased over 400 hours in air, due to oxidation, but leveled off afterwards. The same approach has also been applied to the printing of nickel where oxidation is less marked.