Affective recognition from EEG signals: an integrated data-mining approach

Emotions play an important role in human communication, interaction, and decision making processes. Therefore, considerable efforts have been made towards the automatic identification of human emotions, in particular electroencephalogram (EEG) signals and Data Mining (DM) techniques have been then used to create models recognizing the affective states of users. However, most previous works have used clinical grade EEG systems with at least 32 electrodes. These systems are expensive and cumbersome, and therefore unsuitable for usage during normal daily activities. Smaller EEG headsets such as the Emotiv are now available and can be used during daily activities. This paper investigates the accuracy and applicability of previous affective recognition methods on data collected with an Emotiv headset while participants used a personal computer to fulfill several tasks. Several features were extracted from four channels only (AF3, AF4, F3 and F4 in accordance with the 10–20 system). Both Support Vector Machine and Naïve Bayes were used for emotion classification. Results demonstrate that such methods can be used to accurately detect emotions using a small EEG headset during a normal daily activity

Ultimate limit state design of retaining walls with numerical methods

This paper presents a comparison between the results obtained from simple empirical approaches, and full Finite Element Methods using Eurocode 7 (EC7) for the design of supported excavations. It shows the influence of the current different EC7 implementation strategies for the use of partial factors when using Design Approach 1, both for Combination 1, where the action effects are factored at the end of the calculations, and also for Combination 2, where the soil strength parameters need to be factored and procedures are less clear. The influence of different factors in the results is highlighted for structural forces supported walls with increasing excavation depth and number of props. It shows the differences in prop loads obtained from FEM and empirical approaches and illustrates the challenges that designers face when using EC7

HYD Verifications Using Numerical Methods

HYD, as described in Eurocode 7, is related to the upward flow of water through the soil towards a free surface, such as in front of a retaining wall or in the base of an excavation. The HYD verification, using numerical analysis, can be performed with two different approaches. The first approach is the conventional soil block approach where safety may be checked by calculating the equilibrium of a rectangular block of soil. The second approach is the integration point approach where stability can be verified at every integration point in the numerical analysis by checking that the equilibrium is satisfied for a soil column of negligible width above each point. In this paper, the two approaches are described and their advantages and disadvantages are discussed. Comparisons made using benchmark geometries, extensively studied and discussed between the members of the EC7 Evolution Group 9, on Water Pressures, illustrate that the HYD verification using numerical methods seems very promising. Thorough comparisons between the factors from the two approaches, allow designers to better understand the benefits of using more advanced and robust approaches for such stability verifications

Design of Deep Supported Excavations: Comparison Between Numerical and Empirical Methods

This paper focuses on the derivation of design prop loads for supported excavations in stiff clay with increasing excavation depth and number of prop levels. For multi-propped walls there are a number of empirical graphs to obtain the design prop forces. CIRIA C517 (Twine & Roscoe, 1999) enhancing Terzaghi & Peck's work (Terzaghi & Peck (1967) and Peck (1969)) and making it more relevant in the UK practice, suggests the Distributed Prop Load (DPL) method based on 81 case histories and field measurements of prop loads. Similar guidance and empirical graphs exist in other countries such as the EAB Recommendations in Germany (Recommendations on Excavations: EAB, 3rd Edition, 2014). The design prop loads derived by empirical graphs (both CIRIA and EAB which are widely used in the UK and Germany respectively) and Finite Element methods are compared in the context of Eurocode 7 requirements. The German recommendations give prop loads in better agreement with the numerical analysis results. Suggestions are made to update the CIRIA guidance in line with the German recommendations and give different shapes of pressure distribution for supported walls with different number of prop levels. This can result in more realistic predictions of prop loads for upper layers, particularly in deep excavations, and hence more economic design