Construction schedule risk analysis – a hybrid machine learning approach

The UK commissions about £100 billion in infrastructure construction works every year. More than 50% of them finish later than planned, causing damage to the interests of stakeholders. The estimation of time-risk on construction projects is currently done subjectively, largely by experience despite there are many existing techniques available to analyse risk on the construction schedules. Unlike conventional methods that tend to depend on the accurate estimation of risk boundaries for each task, this research aims to proposes a hybrid method to assist planners in undertaking risk analysis using baseline schedules with improved accuracy. The proposed method is endowed with machine intelligence and is trained using a database of 293,263 tasks from a diverse sample of 302 completed infrastructure construction projects in the UK. It combines a Gaussian Mixture Modelling-based Empirical Bayesian Network and a Support Vector Machine followed by performing a Monte Carlo risk simulation. The former is used to investigate the uncertainty, correlated risk factors, and predict task duration deviations while the latter is used to return a time-risk simulated prediction. This study randomly selected 10 projects as case studies followed by comparing their results of the proposed hybrid method with Monte Carlo Simulation. Results indicated 54.4% more accurate prediction on project delays.

Integrated Geochemical And Mineralogical Investigation of Soil From The Volcanic Fogo Island (Cape Verde): Implications For Ecological And Probabilistic Human Health Risks

Volcanic regions are associated with increased environmental and human health risks due to elevated concentrations of potentially toxic elements (PTEs). Fogo Island, Cape Verde, experienced recent volcanic eruptions, which raised questions about local soils' potential to pose such risks. To better understand the local mineralogy and geochemistry, and environmental and probabilistic human health risks, we (i) investigate the distribution of selected PTEs in 140 soil samples covering different geologic units, (ii) determine major associations between minerals and geological units, (iii) calculate the potential ecological risk, and (iv) model human health risks based on Monte Carlo simulations. The results show that the soils overlaying the older pre-caldera units yield higher contents of secondary minerals (phyllosilicates and Fe-oxides), with relative enrichment of PTEs. The soils covering more recent units are enriched with primary minerals (feldspar and pyroxene) and show elevated concentrations of Pb. This study suggests that As, Pb, Cd and Hg pose ‘considerable’ to ‘very high’ ecological risks. Based on probabilistic health risk simulation, ingestion is identified as the dominant pathway of PTEs exposure. Metal(oid)s are unlikely to cause a non-carcinogenic health risk, although As may pose a cancer risk for children. This research also provides health and environmental authorities with a tool to manage such risks.

Effects of barley and triticale silage based diets and residual feed intake on performance, profitability, and predicted CO2e emission of backgrounding steers

Background Feed costs are the largest expense in commercial beef production. Increasing cattle (Bos taurus) feed efficiency should reduce feed costs and increase beef profitability. This study used data from two years of a backgrounding trial conducted in Lacombe, Alberta, Canada. The evaluation looked at economic and predicted CH4 emission impacts of diet quality and cattle efficiency type in backgrounding systems. The hypothesis was that diet quality from use of barley (Hordeum vulgare c.v. Canmore) or triticale (x Triticosecale c.v. Bunker) silage-based diets and cattle efficiency type would interact to affect profitability and CH4 emissions. Results The experimental design was a four (cattle efficiency type; defined by residual feed intake (RFI)) by two (barley or triticale silage-based rations) factorial treatment with two replicates (pen of eight steers)/treatment/year over two years. Year was a random blocking factor. Cattle weight, intake, and diet composition data were combined with market prices to assess profitability. Methane emissions data were predicted from observed performance using a nutrient requirement model. Effects of diet and cattle efficiency type on profitability and CO2e emissions were assessed using statistical and stochastic risk simulation. By supporting greater gain and feed efficiency, the barley silage diet provided higher net revenue (NR) and lower CO2e emission (P < 0.01 for both). The NR was affected by observed pen average RFI. Risk simulation showed preference for efficient steers and use of barley silage-based diets. Conclusions The profitability of beef backgrounding was affected by cattle efficiency type and diet quality with higher quality diets also lowering CO2e emission and little evidence of interaction between cattle efficiency type and diet quality. The difference in certainty equivalent (~$30/steer) of efficient steers on barley silage and inefficient steers on barley silage or efficient or inefficient steers on triticale silage supports a beef backgrounding producer focus on diet quality and cattle efficiency type. However, inefficient steers on barley silage still generated higher certainty equivalent per steer than efficient or inefficient steers on triticale silage. This study did not address potential agronomic differences, including yield, which could provide nuance to forage choice.

Μέτρηση δεικτών οξειδωτικού στρες σε ιστούς και αίμα αρουραίων μετά από χορήγηση μείγματος φυτοφαρμάκων και συντηρητικών τροφίμων σε μικρές δόσεις, για μεγάλο χρονικό διάστημα

Η μακροχρόνια έκθεση του ανθρώπου σε ξενοβιοτικές ουσίες επιφέρει αυξημένο κίνδυνο εμφάνισης διαφόρων νόσων. Πολλές έρευνες έχουν πραγματοποιηθεί για τη μελέτη της επίδρασης της μακροχρόνιας έκθεσης μεμονωμένων χημικών ουσιών σε χαμηλές δόσεις στην οξειδοαναγωγική κατάσταση διαφόρων οργανισμών. Η ιδέα της χορήγησης ενός μείγματος χημικών ουσιώνσε δόσεις μικρότερες του NOAEL (No observed adverse effect level) που παρουσιάζεται στην πειραματική αυτή μελέτη είναι πρωτοποριακή. Με τη μελέτη αυτή προσεγγίστηκε η προσομοίωση κινδύνου σε ρεαλιστικά σενάρια (real-life risk simulation). Σκοπός της παρούσας διατριβής ήταν να αξιολογηθεί η επίδραση που έχει ένα μείγμα ξενοβιοτικών ουσιών που χορηγήθηκε για μεγάλο χρονικό διάστημα σε συγκεντρώσεις χαμηλότερες από το NOAEL, στο οξειδοαναγωγικό προφίλ επιμύων. Για το σκοπό αυτό χρησιμοποιήθηκαν 40 επίμυες στους οποίους χορηγήθηκε για 18 μήνες, μείγμα 13 χημικών ουσιών (καρβαρύλιο, διμεθοϊκό, γλυφοσικό, μεθομυλεστέρας, μεθυλοπαραθείον, τριαδιμεθόνη, ασπαρτάμη, βενζοϊκό νάτριο, τετραοξικό δινάτριο αιθυλενοδιαμίνης (EDTA), αιθυλοπαραβένιο, βουτυλοπαραβένιο, διφαινόλη Α και αραβικό κόμμι) σε 3 δόσεις (μικρή, μεσαία, μεγάλη).Στους 6, 12 και 18 μήνες πραγματοποιήθηκε μέτρηση βιοδεικτών οξειδοαναγωγής στο αίμα ενώ στους 18 μήνες και στους ιστούς των ζώων. Σύμφωνα με τα αποτελέσματα των βιοδεικτών του αίματος στους 6 και 12 μήνες η έκθεση στη μικρή συγκέντρωση του μείγματος και στους 18 μήνες στη μικρή και στη μεσαία συγκέντρωση προκάλεσε φυσιολογικές προσαρμογές, ενισχύοντας τον αντιοξειδωτικό μηχανισμό. Αντίθετα, η έκθεση στο μείγμα στη μεγαλύτερη δόση στους 18 μήνες προκάλεσε σημαντική διαταραχή στην οξειδοαναγωγική ισορροπία του αίματος και των ιστών, επομένως οξειδωτικό στρες. Η εργασία αυτή καταδεικνύει ότι η χρόνια χορήγηση ξενοβιοτικών που εκτίθεται ο άνθρωπος στην καθημερινότητά του, ακόμα και σε πολύ μικρές συγκεντρώσεις προκαλεί οξειδωτικό στρες. Επομένως, με βάση τα δεδομένα αυτής αλλά και άλλων παρόμοιων μελετών προκύπτει ότι ίσως θα πρέπει να επανεξεταστούν οι διαδικασίες κατά τις οποίες ορίζονται οι επιβλαβείς και οι ακίνδυνες δόσεις διαφόρων ξενοβιοτικών για τον άνθρωπο.

Application of the asymptotic theory of extreme values to risk simulation of breaking-out of large forest fires

Issues of applying the asymptotic theory of extreme values to the risks analysis of breaking-out of the largest-area yearly forest fires, were considered. As original material, the paper authors used data on areas of the forest fires occurring in the south of Russia’s Khabarovsk Territory from 1968 to 2017. For each year, the largest-area forest fire was selected from the considered period of time. In all, 50 fires were selected for this period of time (according to quantity of the years in the period). This sample analysis showed that the general population of these fires areas (where the sample was selected) has probability distribution of extreme values of the first type. An analytical expression for the probability distribution function of this general population was received. On the basis of this distribution analysis, a forecast was made concerning risks of the breaking-out and the average recurrence periods of such fires for various values of the burning area. The conducted analysis showed that in 87.5% of cases, in the south of Khabarovsk territory, the largest-area yearly forest fires, with an area of from 50 to 400 km2, will break out with the 1.2 years recurrence interval. In other words, almost every year, with the exception of these rare events when fires with other areas will occur. It was supposed that the probability distribution of extreme values of the first type can be applied not only to the forest area of Russia’s Khabarovsk territory, but also to other zones in the world with large forest areas.