There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

This presentation is a case study taken from the travel and holiday industry. Paxport/Multicom, based in UK and Sweden, have recently adopted a recommendation system for holiday accommodation bookings. Machine learning techniques such as Collaborative Filtering have been applied using Python (3.5.1), with Jupyter (4.0.6) as the main framework. Data scale and sparsity present significant challenges in the case study, and so the effectiveness of various techniques are described as well as the performance of Python-based libraries such as Python Data Analysis Library (Pandas), and Scikit-learn (built on NumPy, SciPy and matplotlib). The presentation is suitable for all levels of programmers.

Machine learning with Python

The finite element analysis of dynamic problems in an infinite, isotropic medium is discussed. To simulate the physically infinite system by a finite model, an energy absorbing boundary is proposed. This boundary is frequency independent and proves to be very efficient in absorbing stress waves. The boundary constants are calculated for the particular cases of plane strain and axisymetry. /Author/TRRL/

Unified boundary for finite dynamic models

L'article suivant donne une description de la methode theorique pour le calcul du danger d'un soulevement du fond d'une fouille cadragee dans l'argile. Terzaghi et Tschebotarioff ont deja donne des formules pour un pareil calcul, mais ces formules ne sont valables que pour des fouilles de petite profondeur. Basee sur les formules de la capacite portante des fondations dans l'argile, une nouvelle solution du probleme de soulevement du fond a ete developpee. La profondeur critique d'une fouille est donnee par : D c = N c . S/γ ou s et γ sont respectivement la resistance au cisaillement et le poids d'unite de l'argile, N c etant un coefficient sans dimension et dependant de la forme de la fouille, c'est-a-dire de la proportion largeur-longueur et de la proportion profondeur-largeur. Les valeurs de N c , identiques aux valeurs donnees par Skempton (1951) pour la capacite portante, sont montrees graphiquement dans la Figure 2. La validite de ces formules a ete examinee par comparaison de quatorze fouilles. Dans sept de ces fouilles, un soulevement total du fond a eu lieu, les coefficients theoriques de securite donnant comme valeur moyenne de 0,96. Quatre fouilles, ou on constatait un soulevement partiel du fond, ont fourni une valeur moyenne des coefficients theoriques de securite de 1,11. Les trois dernieres fouilles ont ete accomplies sans evenement speciaux, mais des observations sur place indiquaient que, avec une profondeur agrandissante, on aurait du craindre un soulevement du fond, la valeur moyenne des coefficients theoriques de securite etant de 1,08. Les resultats obtenus ci-dessus montrent, ainsi, que la methode decrite nous permet d'estimer avec une precision suffisante le danger d'un soulevement du fond d'une fouille dans l'argile, et que la methode suffit pour la plupart des usages pratiques.

Stability of strutted excavations in clay

Digital twin aided sustainability-based lifecycle management for railway turnout systems

In recent years, there has been an increasing interest in the application of machine learning for the prediction of pavement performance. Prediction models are used to predict the future pavement c...

Machine learning approach for pavement performance prediction

Transition zones to railway bridges: Track measurements and numerical modelling

The initial geometry of a railway track continually degrades over its life-cycle. Changes in the track alignment give rise to variations in the dynamic axle load which accelerate track degradation,...

/pdf/design-and-construction-of-backfills-for-railway-track-1nseavjjmb.pdf

Design and construction of backfills for railway track transition zones

The effect of differential settlements on the dynamic response of the train–track system: A numerical study

In railway lines, transition zones between different track support conditions normally evidence higher degradation rates, thus requiring additional maintenance to ensure safety and service quality. Studies based on numerical simulations indicate that under sleeper pads (USP) can minimise those degradation rates. The study presented herein focuses on the influence of USP on the dynamic behaviour of transitions to underpasses, in an attempt to fill the gap between numerical and field studies. To that aim, the authors used finite element method models, calibrated and validated with field measurements. These models take into account the train–track interaction and include all relevant track components and backfill geomaterials. This study shows that soft USP have a significant influence over the track's dynamic behaviour: amplifying rail displacements and sleeper accelerations, and inducing abrupt variations in the track vertical stiffness and oscillations in train–track forces. To benefit from the use of USP...

/pdf/under-sleeper-pads-in-transition-zones-at-railway-1qs2vgl1qp.pdf

Eduardo Fortunato

Papers

Machine learning approach for pavement performance prediction

Transition zones to railway bridges: Track measurements and numerical modelling

Design and construction of backfills for railway track transition zones

The effect of differential settlements on the dynamic response of the train–track system: A numerical study

Under sleeper pads in transition zones at railway underpasses: numerical modelling and experimental validation