Modeling and evaluation of causal factors in emergency responses to fire accidents involving oil storage system

According to the statistics of 160 typical fire and explosion accidents in oil storage areas at home and abroad nearly 50 years, 122 of them occurred the secondary accidents in the emergency responses. Based on 122 accident cases, 21 causal factors leading to secondary accidents are summarized. In order to quantify the influencing degree of these causal factors on the accident consequences, a multiple linear regression model was established between them. In the modeling process, these factors are decomposed into the criterion layer, variable layer, and bottom layer. The improved analytic hierarchy process (IAHP) was used to establish the relationship between the bottom factors and variable factors, and the regression analysis method was used to establish the relational model between variable layer and criterion layer. For 122 cases of the secondary accidents, this study took the year as a statistical dimension, and obtained 40 groups of sample data. The first 34 groups of sample data were used to build the causal factors model, and the last 6 groups of sample data were tested the generalization ability of the model by using the established regression model combined with grey prediction model. The results show that the prediction ability of the established model was better than that of the grey prediction model alone. Moreover, the relative contribution and change trend of the causal factors were evaluated using the mutation progression method, and corresponding preventive countermeasures were proposed. It was found that human professional skills, knowledge and literacy, environmental issues, and firefighting facilities are the main influencing factors that lead to the secondary accidents. These three kinds of factors show a gradual improvement trend, and the existing prevention measures should be maintained and further improved. The problem of inherent objects or equipment factors has not been effectively improved and has a worsening trend, which is the focus of prevention in the future, and the prevention and control efforts need to be moderately increased. The research results have important guiding significance for understanding the quantitative influences of causal factors on the accident consequences, improving emergency response capabilities, reducing accident losses, and avoiding secondary accidents.

Thickness Dependent Properties of Ultrathin Perovskite Nanosheets with Ruddlesden-Popper-like Atomic Stackings

Ruddlesden–Popper perovskites possess rich variety and multiple phases due to their mixed organic cations and variable layer numbers. However, the direct observation of these phases and their optical performance in...

Phytoplankton Dynamics in the Middle Adriatic Estuary, with a Focus on the Potentially Toxic Genus Pseudo-nitzschia

The Krka River estuary is a karstic, permanently stratified estuary due to the strong freshwater inflow. It is a special environment in which to study the phytoplankton community, especially because this area is an important aquaculture site. Among other potentially toxic phytoplankton species, the diatom genus Pseudo-nitzschia occurs frequently and is a potential source of domoic acid (DA), causing shellfish toxicity and human intoxication. The main objective was to examine the dynamics of the phytoplankton community and, in particular, the genus Pseudo-nitzschia in the upper part of the Krka estuary, through monthly sampling over two years. The phytoplankton community was analysed using light microscopy and scanning electron microscopy to determine the diversity of Pseudo-nitzschia species and characterise the environmental parameters associated with a high abundance of Pseudo-nitzschia species. Seven Pseudo-nitzschia species were identified in the investigation, with higher frequencies and abundances in the less variable layer, at a 7 m depth. Blooms of Pseudo-nitzschia were noted in the late summer/early autumn, dominated by P. delicatissima/arenysensis. Winter assemblages were characterised by P. pseudodelicatissima/cuspidata, P. calliantha, and P. subfraudulenta, and were associated with domoic acid occurrence in shellfish.

Design of Robust Total Site Heat Recovery Loops via Monte Carlo Simulation

For increased total site heat integration, the optimal sizing and robust operation of a heat recovery loop (HRL) are prerequisites for economic efficiency. However, sizing based on one representative time series, not considering the variability of process streams due to their discontinuous operation, often leads to oversizing. The sensitive evaluation of the performance of an HRL by Monte Carlo (MC) simulation requires sufficient historical data and performance models. Stochastic time series are generated by distribution functions of measured data. With these inputs, one can then model and reliably assess the benefits of installing a new HRL. A key element of the HRL is a stratified heat storage tank. Validation tests of a stratified tank (ST) showed sufficient accuracy with acceptable simulation time for the variable layer height (VLH) multi-node (MN) modelling approach. The results of the MC simulation of the HRL system show only minor yield losses in terms of heat recovery rate (HRR) for smaller tanks. In this way, costs due to oversizing equipment can be reduced by better understanding the energy-capital trade-off.

Условия достижения сверхтвердого состояния при критической наноразмерной толщине слоев в многопериодных вакуумно-дуговых нитридных покрытиях

Possible mechanisms of the interfacial interaction in multiperiodic (bilayer) compositions at critical thicknesses (as small as below 10 nm) of conjugated phases have been studied for the first time using structure analysis, numerical simulations, and measurements of mechanical characteristics. For attaining a state of superhigh hardness (above 40 GPa), it is proposed to form coatings with variable layer thicknesses in the bilayer period Λ. Using this approach, 10-μm-thick coatings of the TiN/ZrN system with hardness above 44 GPa were obtained for a bilayer period of Λ ≈ 10 nm with a layer thickness ratio of 1.5/1.