Integrated Expert Management Knowledge on OSI Network Management Objects

The management of modern telecommunications networks must satisfy ever-increasing operational demands. We propose a study for the improvement of intelligent administration techniques in telecommunications networks. This task is achieved by integrating knowledge base of expert system within the management information used to manage a network. For this purpose, an extension of OSI management framework specifications language has been added and investigated. For this goal, we shall use the language Guidelines for the Definition of Managed Objects (GDMO) and a new property named RULE which gathers important aspects of the facts and the knowledge base of the embedded expert system. Networks can be managed easily by using this proposed integration

Influence of Exposure Environments on the Durability of Slag-Blended Cements

Both chlorides and sulphates combine in seawater to affect the durability of reinforced concrete structures located in marine environments. This paper presents the results of an experimental study on slag blended cement systems, cured for 7 days, before exposure to a combined solution of sodium chloride (30 g/L) and sodium sulphate (3 g/L). Two slags of different chemical compositions, designated as slags 1 and 2 were respectively blended with Portland cement CEM I 52.5R at 30 and 70 wt.% replacement levels. Mechanical tests on mortar samples were complemented by microstructural examination and chemical characterisation on paste samples, all using a constant w/b ratio of 0.5, to investigate the influence of exposure environment. The exposure environments include water and ponding in combined chloride-sulphate solution at 20 °C and 38 °C (to reflect temperate and tropical climates). The results show that temperature has a significant effect on the durability of slag blends. Reduced sorptivity at higher temperature led to reduced chloride penetration at early age. This effect is less so at later age. Compressive strength generally improved with increase in chloride penetration. SEM-EDX elemental analysis provided a good basis for following chloride penetration profile. XRD analysis showed the conversion of monosulphate to ettringite, Friedel’s salt and Kuzel’s salt upon exposure to salt solution, which possibly led to improved sorptivity and mechanical properties

Effects of Temperature and Curing Duration on the Stability of Slag Cements in Combined Chloride-Sulphate Environments

This experimental study investigates the effects of temperature and curing duration on the stability of slag blended cement systems exposed at 20 °C and 38 °C to combined sodium chloride (30 g/L) – sodium sulphate (3 g/L) solutions. Two slags, designated as slag 1 and 2, having CaO/SiO2 ratios of 1.05 and 0.94, were respectively blended with Portland cement CEM I 52.5R at 30 wt.% replacement level. Mortar prisms and cubes with w/b ratio of 0.5 and binder/aggregate ratio of 1:3 were then prepared for length and mass changes. The samples were cured in lime water for either 7 or 28 days before ponding for a total exposure period of 544 days. Analogous paste samples were also prepared to follow changes in the hydration products using x-ray diffraction (XRD). The results showed that curing at 38°C resulted in less expansion and prolonged curing generally reduced expansion except for slag 1 blend at 20 °C. Also, mass-change was minimal at 38 °C compared to 20 °C, and curing up to 28 days further improved mass stability. There was a positive correlation between mass change and length change for the period of investigation

Effects of Accelerated Carbonation Curing on CO2 Sequestration and on the Compressive Strength of Concrete Masonry Units

The global consumption of Portland cement has risen to over 4 billion tonnes per annum. Its manufacture is energy and carbon intensive and approximately 900 kg of CO2 is emitted into the atmosphere for each tonne of Portland cement produced. The International Energy Agency (IEA) roadmap sets out a goal to reduce emissions due to cement production to 18 % below 2006 levels by 2050. Concrete has the potential to re-absorb CO2 by the process of carbonation, where it reacts with CaO in the concrete to form calcium carbonate. Accelerated carbonation curing (ACC) is a technique for curing fresh concrete that can sequester CO2. ACC of concrete masonry units (CMU’s) can reduce the embodied carbon footprint and play a major role in sustainability by reducing global CO2. ACC also offers potential improvements in the mechanical and durability properties of concrete. Experimental work was carried out which involved the ACC of CMU’s at a CO2 concentration of 50% over various time intervals and exposure conditions. It was calculated that the maximum possible CO2 uptake potential of the cement was approximately 49.5%. A CO2 uptake of 23% per mass of cement was achieved after 7 days of ACC along with compressive strength increases of 15.4% and 28% for ACC samples at 7 and 28 days respectively. The study found that the greatest compressive strength increase occurred between 4 and 24 hours. After 24 hours the ACC process showed a similar proportional rate of strength gain over time when compared to the control. The study shows that ACC is different from weathering carbonation as it accelerates the hydration reaction of the unhydrated cement phases C3S and C2S producing rapid strength gains. Weathering carbonation occurs in concrete after the hydration process has been predominately completed and results in the decalcification of C-S-H and the formation of silica gel which is detrimental to the cement paste

ToF-SIMS depth profiling analysis of the uptake of Ba2+ and Co2+ ions by natural kaolinite clay

The sorption behavior of Ba2+ and Co2+ ions on a natural clay sample rich in kaolinite was studied using time-of-flight secondary ion mass spectrometry (ToF-SIMS). Depth profiling at 10-Å steps was performed up to a 70-Å matrix depth of the clay prior to and following sorption. The results showed that Co2+ is sorbed in slightly larger quantities than Ba2+, with significant numbers of ions fixed on the outermost surface of the clay. Depletion of the ions K+, Mg 2+, and Ca2+ from the clay lattice was observed to accompany enrichment with Co2+ and Ba2+ ions. The data obtained using X-ray powder diffraction (XRPD) and scanning electron microscopy (SEM) indicated insignificant structural and morphological changes in the lattice of the clay upon sorption of both Ba2+ and Co2+ ions. Analysis using energy dispersive X-ray spectroscopy (EDS) showed that the average atomic percentage (±S.D.) of Ba and Co on kaolinite surface were 0.49±0.11 and 0.61±0.19, respectively, indicating a limited uptake capacity of natural kaolinite for both ions

Freeze-Thaw Resistance of Concrete: Insight from Microstructural Properties

Composite cements offer low carbon alternatives to conventional CEM I. These binders also generally tend to perform better than CEM I in aggressive chemical environments. However, their freeze-thaw resistance, evident through surface scaling and internal damage is usually impaired. Postulated theories on freeze-thaw induced damage do not fully explain the origin of this weakness in composite cement concretes. This paper systematically presents the phase assemblage changes associated with the freeze-thaw of concrete specimen made from composite cements with and without limestone. The freeze-thaw test was performed on concrete according to CIF method based on CEN/TR 15177 and the corresponding cement pastes characterized by X-ray powder diffraction (XRD) and thermogravimetric analysis (TGA). In all investigated composite cements, portlandite was already depleted after the 7d capillary suction. The implications of this and other modified assemblages during the conditioning and the freeze-thaw test are consequently discussed

Is carbon dioxide pricing a driver in concrete mix design?

The global cement industry is responsible for 7% of anthropogenic carbon dioxide emissions and, as such, has a vital role to play in the transition to a low carbon dioxide economy. In recent years, this has been achieved by technological advances and increased use of supplementary cementitious materials, but the authors have recently shown that there are other means of achieving comparable carbon dioxide savings, for example, by reducing workability. However, price remains a considerable barrier to the widespread implementation of low carbon dioxide concrete. Using the same model for concrete mix design as was used to determine embodied carbon dioxide (ECD), variations in the cost of the components of concrete have now been considered. Considering 24 different mix designs, each spanning a range of characteristic strengths from 20 to 100 MPa, measures to reduce the carbon dioxide footprint were also found to reduce the material cost of the concrete. As such, it may be considered that the construction industry is already encouraged to reduce its ‘carbon footprint’. However, the concept of the carbon footprint was then considered in a more nuanced fashion, considering the ECD per unit strength. On such a basis, the cheapest mixes did not have the lowest ECD. Therefore, the impact of levying a charge on the carbon footprint was considered. To ensure low carbon dioxide concrete is also the cheapest, carbon dioxide emissions would have to be priced approximately one to two orders of magnitude higher than current market value. This would become the dominant factor in construction, with serious consequences for the industry. Furthermore, such charges may pose ethical problems, being viewed as a ‘licence to pollute’ and therefore undermining society's efforts to reduce the carbon dioxide emissions of the construction industry

The short-term impact of the alcohol act on alcohol-related deaths and hospital admissions in Scotland: a natural experiment

Background and aim: The introduction of the Alcohol Act in Scotland on 1 October 2011, which included a ban on multi-buy promotions, was likely associated with a fall in off-trade alcohol sales in the year after its implementation. The aim of this study was to test if the same legislation was associated with reduced levels of alcohol-related deaths and hospital admissions in the 3-year period after its introduction. Design: A natural experiment design using time series data to assess the impact of the Alcohol Act legislation in Scotland. Comparisons were made with unexposed populations in the rest of Great Britain. Setting Scotland with comparable data obtained for geographical control groups in other parts of Great Britain. Participants: For alcohol-related deaths, a total of 17,732 in Scotland and 88,001 in England/Wales across 169 four-week periods between January 2001 and December 2013. For alcohol-related hospital admissions, a total of 121,314 in Scotland and 696,892 in England across 182 four-week periods between January 2001 and December 2014. Measurements: Deaths and hospital admissions in Scotland and control groups that were wholly attributable to alcohol for consecutive four-week periods between January 2001 and December 2014. Data were obtained by age, sex and area-based socioeconomic position. Findings: There was no evidence to suggest that the Alcohol Act was associated with changes in the overall rate of alcohol-related deaths [incidence rate ratio (IRR) 0.99, 95% confidence interval (0.91 to 1.07)] or hospital admissions [IRR 0.98 (0.95 to 1.02)] in Scotland. In control group analyses, the pseudo intervention variable was not associated with a change in alcohol-related death rates in England/Wales [IRR 0.99 (0.95 to 1.02)], but was associated with an increase in alcohol-related hospital admission rates in England [IRR 1.05 (1.03 to 1.07)]. In combined models, the interaction analysis did not provide support for a ‘net effect’ of the legislation on alcohol-related deaths in Scotland compared with England/Wales [IRR 0.99 (0.95 to 1.04)], but suggested a net reduction in hospital admissions for Scotland compared with England [IRR 0.93 (0.87 to 0.98)]. Conclusion: The implementation of the Alcohol Act in Scotland has not been associated clearly with a reduction in alcohol-related deaths or hospital admissions in the 3-year period after it was implemented in October 2011

Embodied carbon dioxide in concrete: Variation with common mix design parameters

The transition towards a low-carbon infrastructure requires an understanding of the embodied carbon (eCO 2) associated with concrete. However, much current work on eCO 2 underestimates the complexity of its relationship with concrete mix design. This paper demonstrates how eCO 2 of concrete is not a simple function of strength. Rather, for a given strength, considerable eCO 2 savings can be made by careful attention to basic mix design. Replacement of cement with PFA (pulverised fuel ash) can achieve considerable savings; additionally, using a concrete of lower workability, employing a superplasticiser, using crushed rather than rounded aggregate and using a higher strength of cement can have comparably significant effects. The analysis is presented in terms of embodied carbon per unit strength; this shows that there is an optimum strength for all concretes (with regard to minimising eCO 2 per unit of structural performance) of between 50 and 70 MPa