4,856 research outputs found
Effect of flow pattern at pipe bends on corrosion behaviour of low carbon steek and its challenges
Recent design work regarding seawater flow lines has emphasized the need to identify, develop, and verify critical relationships between corrosion prediction and flow regime mechanisms at pipe bend. In practice this often reduces to an pragmatic interpretation of the effects of corrosion mechanisms at pipe bends. Most importantly the identification of positions or sites, within the internal surface contact areas where the maximum corrosion stimulus may be expected to occur, thereby allowing better understanding, mitigation, monitoring and corrosion control over the life cycle. Some case histories have been reviewed in this context, and the interaction between corrosion mechanisms and flow patterns closely determined, and in some cases correlated. Since the actual relationships are complex, it was determined that a risk based decision making process using selected âwhatâ if corrosion analyses linked to âwhat ifâ flow assurance analyses was the best way forward. Using this in methodology, and pertinent field data exchange, it is postulated that significant improvements in corrosion prediction can be made. This paper outlines the approach used and shows how related corrosion modelling software data such as that available from corrosion models Norsok M5006, and Cassandra to parallel computational flow modelling in a targeted manner can generate very noteworthy results, and considerably more viable trends for corrosion control guidance. It is postulated that the normally associated lack of agreement between corrosion modelling and field experience, is more likely due to inadequate consideration of corrosion stimulating flow regime data, rather than limitations of the corrosion modelling. Applications of flow visualization studies as well as computations with the k-Δ model of turbulence have identified flow features and regions where metal loss is a maximu
Visualisation of trust and quality information for geospatial dataset selection and use:Drawing trust presentation comparisons with B2C e-Commerce
The evaluation of geospatial data quality and trustworthiness presents a major challenge to geospatial data users when making a dataset selection decision. Part of the problem arises from the inconsistent and patchy nature of data quality information, which makes intercomparison very difficult. Over recent years, the production and availability of geospatial data has significantly increased, facilitated by the recent explosion of Web-based catalogues, portals, standards and services, and by initiatives such as INSPIRE and GEOSS. Despite this significant growth in availability of geospatial data and the fact that geospatial datasets can, in many respects, be considered commercial products that are available for purchase online, consumer trust has to date received relatively little attention in the GIS domain. In this paper, we discuss how concepts of trust, trust models, and trust indicators (largely derived from B2C e-Commerce) apply to the GIS domain and to geospatial data selection and use. Our research aim is to support data users in more efficient and effective geospatial dataset selection on the basis of quality, trustworthiness and fitness for purpose. To achieve this, we propose a GEO label â a decision support mechanism that visually summarises availability of key geospatial data informational aspects. We also present a Web service that was developed to support generation of dynamic GEO label representations for datasets by combining producer metadata (from standard catalogues or other published locations) with structured user feedback
An evaluation of the structural integrity of HSLA steels exposed in simulated flue-gases under dynamic conditions for anthropogenic CO2 transport.
Carbon capture and storage (CCTS) is a transitional technology offering a nearterm
method of mitigating climate change. Pipelines are considered to be the
most suitable systems for CCTS; however, structural integrity of pipeline has to
be guaranteed in order for this technology to become a practical technical
solution.
The investigation detailed here is based on a systematic experimental approach
to investigate the structural integrity of API X100, X60 and X70 steels exposed
in simulated flue-gas under dynamic conditions. A core of the structured
experiments through some methods such as aging test, tensile properties,
fracture toughness, residual stress and engineering critical assessment was
accomplished in parent material and exposed samples on flue-gas.
The temperature range of evaluation for tensile test covers -70C to 21C while
fracture toughness was over the range -196C to 21C. Tensile properties of
virgin material show that steels meet standard specification while aging samples
do not show significant scatter compared with parent steels. Ovalisation of the
fracture surface and splitting phenomenon was observed which is related with
steel anisotropy. Fracture toughness obtained from experiment was compared
with that calculate by two existing correlations. However both correlations did
not predict the level of fracture toughness expected indicating the methods used
in this work has limited applicability under the test conditions used here.
Residual stress (RS) induced in API X100 steel by cold rolling method was
characterised using two complementary techniques known as Neutron
Diffraction (ND) and Incremental Hole Drilling (IHD). The RS distribution shows
good agreement for both techniques used but reproducibility of them depends
on their own inaccuracies. An Engineering Criticality Assessment (ECA) was
performed based in Failure Assessment Diagram (FAD) approach using all the
experimental data obtained by a leak-before-break method under three
operational pressures. The results showed the effect on the integrity of material
under the presence of a flaw length assessed.
Overall, the thesis presents a combined engineering critical assessment which
involved the examination of materials used to transport flue-gas and established
a methodology to determine fracture toughness alongside with the FAD to
assess the integrity of pipelines
A Systematic Review of Automated Query Reformulations in Source Code Search
Fixing software bugs and adding new features are two of the major maintenance
tasks. Software bugs and features are reported as change requests. Developers
consult these requests and often choose a few keywords from them as an ad hoc
query. Then they execute the query with a search engine to find the exact
locations within software code that need to be changed. Unfortunately, even
experienced developers often fail to choose appropriate queries, which leads to
costly trials and errors during a code search. Over the years, many studies
attempt to reformulate the ad hoc queries from developers to support them. In
this systematic literature review, we carefully select 70 primary studies on
query reformulations from 2,970 candidate studies, perform an in-depth
qualitative analysis (e.g., Grounded Theory), and then answer seven research
questions with major findings. First, to date, eight major methodologies (e.g.,
term weighting, term co-occurrence analysis, thesaurus lookup) have been
adopted to reformulate queries. Second, the existing studies suffer from
several major limitations (e.g., lack of generalizability, vocabulary mismatch
problem, subjective bias) that might prevent their wide adoption. Finally, we
discuss the best practices and future opportunities to advance the state of
research in search query reformulations.Comment: 81 pages, accepted at TOSE
Enhancing the E-Commerce Experience through Haptic Feedback Interaction
The sense of touch is important in our everyday lives and its absence makes it difficult to explore and manipulate everyday objects. Existing online shopping practice lacks the opportunity for physical evaluation, that people often use and value when making product choices. However, with recent advances in haptic research and technology, it is possible to simulate various physical properties such as heaviness, softness, deformation, and temperature. The research described here investigates the use of haptic feedback interaction to enhance e-commerce product evaluation, particularly haptic weight and texture evaluation. While other properties are equally important, besides being fundamental to the shopping experience of many online products, weight and texture can be simulated using cost-effective devices.
Two initial psychophysical experiments were conducted using free motion haptic exploration in order to more closely resemble conventional shopping. One experiment was to measure weight force thresholds and another to measure texture force thresholds. The measurements can provide better understanding of haptic device limitation for online shopping in terms of the availability of different stimuli to represent physical products. The outcomes of the initial psychophysical experimental studies were then used to produce various absolute stimuli that were used in a comparative experimental study to evaluate user experience of haptic product evaluation.
Although free haptic exploration was exercised on both psychophysical experiments, results were relatively consistent with previous work on haptic discrimination. The threshold for weight force discrimination represented as downward forces was 10 percent. The threshold for texture force discrimination represented as friction forces was 14.1 percent, when using dynamic coefficient of friction at any level of static coefficient of friction. On the other hand, the comparative experimental study to evaluate user experience of haptic product information indicated that haptic product evaluation does not change user performance significantly. However, although there was an increase in the time taken to complete the task, the number of button click actions tended to decrease. The results showed that haptic product evaluation could significantly increase the confidence of shopping decision. Nevertheless, the availability of haptic product evaluation does not necessarily impose different product choices but it complements other selection criteria such as price and appearance.
The research findings from this work are a first step towards exploring haptic-based environments in e-commerce environments. The findings not only lay the foundation for designing online haptic shopping but also provide empirical support to research in this direction
Validation of in situ applicable measuring techniques for analysis of the water adsorption by stone
As the water adsorbing behaviour (WAB) of stone is a key factor for most degradation processes, its analysis is a decisive aspect when monitoring deterioration and past conservation treatments, or when selecting a proper conservation treatment. In this study the performance of various non-destructive methods for measuring the WAB are compared, with the focus on the effect of the variable factors of the methods caused by their specific design. The methods under study are the contact-sponge method (CSM), the Karsten tube (KT) and the Mirowski pipe (MIR). Their performance is compared with the standardized capillary rise method (CR) and the results are analysed in relation to the open porosity of different lithotypes. Furthermore the effect of practical encumbrances which could limit the application of these methods was valuated. It was found that KT and CSM have complementary fields of investigation, where CSM is capable of measuring the initial water uptake of less porous materials with a high precision, while KT was found commodious for measuring longer contact times for more porous lithotypes. MIR showed too many discommodities, leading to unreliable results. To adequately compare the results of the different methods, the size of the contact area appears to be the most influential factor, whereas the contact material and pressure on the surface do not indicate a significant influence on the results. The study of these factors is currently being extended by visualization of the water adsorption process via X-ray and neutron radiography in combination with physico-mathematical models describing the WAB
Molecular dynamics of high temperature hydrogen attack
High temperature hydrogen attack (HTHA) is a damage mechanism that only affects carbon steel and low alloy material. Most of the data regarding HTHA are experimental-driven. Even though this approach has been successful, there are still much more things that the oil and gas industry does not understand about HTHA. The regions that were considered safe (below the Nelson curves) have experienced catastrophic failure. Our research consists of performing Molecular Dynamics (MD) and the Nudge Elastic Band (NEB) calculation of HTHA to better understand the atomistic behavior of this damage mechanism
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