Impact of Firefighting Sprays on the Fire Performance of Structural Steel Members

Fire Technology - The feasibility of coupled computational fluid dynamics (CFD) and finite element (FE) simulations to aid the planning of fire intervention tactics and the effectiveness of...     

A model for a long-term diffusion of multispecies in concrete based on ion–cement-hydrate interaction

A model for simulating a long-term diffusion in concrete under submerged conditions has been developed. The model focuses on the interaction between cement hydrates and electrolyte solution adopting the physical properties of concrete as alternative parameters for estimating long-term diffusion. The model was verified by the large variety of long-term experimental data involving verification of cement hydrates, porosity properties, pH value, element distribution, and chloride penetration for sulphate-resistant Portland cement (SRPC) concretes. Evaluating impacts of hundreds of years’ exposure on concrete durability, a simulation was also performed for an exposure time of 500 years. The results confirmed the importance of ion–cement-hydrate interaction in the evaluation of a long-term diffusion of harmful substances such as chlorides into concrete. The simulation results show also that the solid phases of the SRPC concrete mix that was used are stable in the long-term. The threshold concentration of chlorides which may initiate reinforcement corrosion defined as Cl^?/OH^? ratio could be exceeded in concrete after moderate exposure period under the conditions investigated with typical protective concrete layers. Using of case-specific values for a threshold chloride content and evaluating the method used for estimating the initiation time of reinforcement corrosion are recommended in the structures with a long-design service life.     

Seismic probabilistic safety analysis of unit 1 of the Loviisa nuclear power plant

The seismic probabilistic safety assessment consists of five phases. In the seismic hazard analysis the seismicity of the plant site is quantified. In the second phase, the structural response of plant buildings is evaluated. On the basis of structural response, the seismic fragilities of selected plant components are developed. In the following phase, the plant logic in the form of fault trees and event trees is established. In the last step, quantification of the core damage risk on the basis of the above information is carried out. For the median value of the annual core damage frequency, a value of 4.4 × 10⁻⁷ was determined.     

Boundary element analysis of a plate on elastic foundations

The objective of this study is to examine the applicability of the boundary element method to analysing a plate on elastic foundation. The fundamental solution of the problem is presented as a Fourier-Bessel integral. For the computation of the values of the fundamental solution an algorithm was developed in which the Fourier-Bessel integral was decomposed into an alternative convergent sequence. Equations based on the direct and indirect boundary element method were derived for a plate situated on a one- or two-parametric elastic foundation. According to the theory presented, computer programs based on the direct and indirect boundary element method were developed. These programs can be used for examining the behaviour of a smooth-boundary plate on a one- or two-parametric elastic foundation. The computer programs were tested by several examples. The results obtained by using a small number of boundary elements compared favourably to the results obtained by a fine finite element mesh. The study shows that the boundary element method is applicable to the analysis of a plate on elastic foundation.     

Measurement of 'blocking antibodies' to pollen antigens by radiolabelled protein A from Staphylococcus aureus

Radiolabelled protein A from Staphylococcus aureus (125I-SpA) was utilized to measure the relative concentrations of the so-called 'blocking antibodies' (BA) in sera from patients subjected to two different forms of desensitization therapy. In addition, sera from rabbits immunized actively with pollen antigens were assayed. Antigens coupled to CNBr-activated papear discs were used as solid phase, and BA bound to the solid-phase antigens were detected by 125I-SpA. The results obtained with this technique correlated excellently with those of a double-antibody technique for IgG, indicating the 125I-SpA assay to be suitable for the measurement of the antigen-specific IgG. The BA concentration in sera from patients subjected to conventional injection therapy increased significantly during the treatment period, whereas no increase could be detected in sera from patients subjected to sublingual treatment. The increases in BA concentrations of rabbit antisera to pollen antigens could be readily traced by this technique.     

The effect of seasonal variation on automated land cover mapping from multispectral airborne laser scanning data

Multispectral airborne laser scanning (MS-ALS) sensors are a new promising source of data for automated mapping methods. Finding an optimal time for data acquisition is important in all mapping applications based on remotely sensed datasets. In this study, three MS-ALS datasets acquired at different times of the growing season were compared for automated land cover mapping and road detection in a suburban area. In addition, changes in the intensity were studied. An object-based random forest classification was carried out using reference points. The overall accuracy of the land cover classification was 93.9% (May dataset), 96.4% (June) and 95.9% (August). The use of the May dataset acquired under leafless conditions resulted in more complete roads than the other datasets acquired when trees were in leaf. It was concluded that all datasets used in the study are applicable for suburban land cover mapping, however small differences in accuracies between land cover classes exist.     

Analysis of short fibres orientation in steel fibre-reinforced concrete (SFRC) by X-ray tomography

The mechanical properties of fibre composite materials are largely determined by the orientation of fibres within the matrix. Which orientation distribution short fibres follow in different parts of a structural element is still a subject for research and discussions in the scientific community. In this article, we present a modern and advanced method for measuring the orientation of short fibres in steel fibre-reinforced concrete (SFRC) by X-ray microtomography. With this method, a voxel image of the fibres is obtained directly in 3D, and the orientation of each individual fibre is calculated based on a skeletonized representation of this image. Scans of 12 SFRC samples, taken from the central height region of real-size floor slabs, reveal the fibres to be mostly horizontally oriented near the centre of a floor slab and more vertically oriented near the edge; here the alignment with the formwork dominates. The fibre orientation distributions are characterized by several orientation parameters as quantitative measures for the alignment. On the practical side, this method has the potential to be incorporated into the development and production process of SFRC structures to verify how the fibres contribute to capacity.     

Corrosion mechanism of hot-dip galvanised reinforcement bar in cracked concrete

In this paper, probable corrosion mechanisms of hot-dip galvanised reinforcement bar in cracked concrete based on long-term durability tests and other studies are determined. The fist mechanism consists of a local dissolution of eta (η) and zeta (ζ) phase. In the second mechanism due to non-uniform zinc coating local dissolution of eta (η) and zeta (ζ) phase together with longitudinal and perpendicular cracking in zinc layer may lead to separation of zinc layer. In the third mechanism due to non-uniform zinc coating full dissolution of eta (η) and partial dissolution of zeta (ζ) phase together with longitudinal and perpendicular cracking in ferrite may lead to separation of zinc layer and ferrite. Corrosion rate with used cement type was decreasing. That is not dependent on concrete quality. However, concrete type has an effect on corrosion rate and moisture conditions.     

The psychophysiology of James Bond: Phasic emotional responses to violent video game events.

The authors examined emotional valence- and arousal-related phasic psychophysiological responses to different violent events in the first-person shooter video game "James Bond 007: NightFire" among 36 young adults. Event-related changes in zygomaticus major, corrugator supercilii, and orbicularis oculi electromyographic (EMG) activity and skin conductance level (SCL) were recorded, and the participants rated their emotions and the trait psychoticism based on the Psychoticism dimension of the Eysenck Personality Questionnaire--Revised, Short Form. Wounding and killing the opponent elicited an increase in SCL and a decrease in zygomatic and orbicularis oculi EMG activity. The decrease in zygomatic and orbicularis oculi activity was less pronounced among high Psychoticism scorers compared with low Psychoticism scorers. The wounding and death of the player's own character (James Bond) elicited an increase in SCL and zygomatic and orbicularis oculi EMG activity and a decrease in corrugator activity. Instead of joy resulting from victory and success, wounding and killing the opponent may elicit high-arousal negative affect (anxiety), with high Psychoticism scorers experiencing less anxiety than low Psychoticism scorers. Although counterintuitive, the wounding and death of the player's own character may increase some aspect of positive emotion. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sleepiness,sleep, and use of sleepiness countermeasures in shift-working long-haul truck drivers

Driver sleepiness is a prevalent phenomenon among professional drivers working unconventional and irregular hours. For compromising occupational and traffic safety, sleepiness has become one of the major conundrums of road transportation. To further elucidate the phenomenon, an on-road study canvassing the under-explored relationship between working hours and sleepiness, sleep, and use of sleepiness countermeasures during and outside statutory rest breaks was conducted. Testing the association between the outcomes and working hours, generalized estimating equations models were fitted on a data collected from 54 long-haul truck drivers (mean 38.1 ± 10.5 years, one female) volunteering in the 2-week study. Unobtrusive data-collection methods applied under naturalistic working and shift conditions included the Karolinska Sleepiness Scale (KSS) measuring sleepiness, a combination of actigraphy and sleep-log measuring sleep, and self-report questionnaire items incorporated into the sleep-log measuring the use of sleepiness countermeasures during and outside statutory rest breaks. Drivers’ working hours were categorized into first and consecutive night, morning and day/evening shifts based on shift timing. The results reveal severe sleepiness (KSS ≥ 7) was most prevalent on the first night (37.8%) and least on the morning (10.0%) shifts. Drivers slept reasonably well prior to duty hours, with main sleep being longest prior to the first night (total sleep time 7:21) and shortest prior to the morning (total sleep time 5:43) shifts. The proportion of shifts whereby drivers reported using at least one sleepiness countermeasure outside statutory rest breaks was approximately 22% units greater for the night than the non-night shifts. Compared to the day/evening shifts, the odds of severe sleepiness were greater only on the first night shifts (OR 6.4–9.1 with 95% confidence intervals, depending on the statistical model), the odds of insufficient daily sleep were higher especially prior to the consecutive night shifts (OR 3.5 with 95% confidence intervals), and the odds of using efficient sleepiness countermeasures outside statutory rest breaks were greater on the first as well as consecutive night shifts (OR 4.0–4.6 with 95% confidence intervals). No statistically significant association was found between shift type and use of efficient sleepiness countermeasures during statutory rest breaks. In all, the findings demonstrate marked differences in the occurrence of severe sleepiness at the wheel, sleep preceding duty hours, and the use of sleepiness countermeasures between different shift types. In addition, although drivers slept reasonably well in connection with different shift types, the findings imply there is still room for improvement in alertness management among this group of employees.