Structural modelling of cost overrun factors in construction industry

Construction industry contributes significantly in improving socio-economic growth of a country. However, this industry usually faces chronic problems such as time overrun, cost overrun, poor quality and others. Of all these, cost overrun is a major problem that occurs globally including Malaysia. Cost overrun is resulted from various factors which are essential to identify for improving cost performance in construction project. Hence, this study focused on identifying and modelling the factors of cost overrun for construction projects in Malaysia. Data collection was done through structured questionnaire, which was designed based on 78 factors found from the literature. Qualitative pilot study was done based on the opinions of 15 experts in the construction industry to improve the questionnaire by reducing the factors to 58. The questionnaire survey was carried out among clients, consultants and contractors. A total of 231 questionnaires were collected of which 213 responses were found valid. Partial Least Square Structural Equation (PLS-SEM) model was developed based on 8 categories/constructs generated through factor analysis test and found that Global Fit Index (GOF) of the model to be 0.37. The findings from the model indicate that all the 8 categories have significant effect on the cost overrun. The most significant category is contractor's site management related issues with path co-efficient value of 0.448. The developed model was validated statistically (using power analysis and predictive relevancy) and through interviewing 21 experienced practitioners. Statistical validation tests showed that the developed model had achieved substantial power in explaining cost overrun problem. All the experts agreed with the factors and also categories of the model have significant impact to cost overrun

CEAI: CCM based Email Authorship Identification Model

In this paper we present a model for email authorship identification (EAI) by employing a Cluster-based Classification (CCM) technique. Traditionally, stylometric features have been successfully employed in various authorship analysis tasks; we extend the traditional feature-set to include some more interesting and effective features for email authorship identification (e.g. the last punctuation mark used in an email, the tendency of an author to use capitalization at the start of an email, or the punctuation after a greeting or farewell). We also included Info Gain feature selection based content features. It is observed that the use of such features in the authorship identification process has a positive impact on the accuracy of the authorship identification task. We performed experiments to justify our arguments and compared the results with other base line models. Experimental results reveal that the proposed CCM-based email authorship identification model, along with the proposed feature set, outperforms the state-of-the-art support vector machine (SVM)-based models, as well as the models proposed by Iqbal et al. [1, 2]. The proposed model attains an accuracy rate of 94% for 10 authors, 89% for 25 authors, and 81% for 50 authors, respectively on Enron dataset, while 89.5% accuracy has been achieved on authors' constructed real email dataset. The results on Enron dataset have been achieved on quite a large number of authors as compared to the models proposed by Iqbal et al. [1, 2]

Leveraging Personalization To Facilitate Privacy

Online social networks have enabled new methods and modalities of collaboration and sharing. These advances bring privacy concerns: online social data is more accessible and persistent and simultaneously less contextualized than traditional social interactions. To allay these concerns, many web services allow users to configure their privacy settings based on a set of multiple-choice questions. We suggest a new paradigm for privacy options. Instead of suggesting the same defaults to each user, services can leverage knowledge of users' traits to recommend a machine-learned prediction of their privacy preferences for Facebook. As a case study, we build and evaluate MyPrivacy, a publicly available web application that suggests personalized privacy settings. An evaluation with 199 users shows that users find the suggestions to be appropriate and private; furthermore, they express intent to implement the recommendations made by MyPrivacy. This supports the proposal to put personalization to work in online communities to promote privacy and security

Etude numérique et expérimentale de l'écoulement autour d'un rotor éolien

An improved model of an actuator surface is proposed, representing the flow around a wind turbine. This model was developed in conjunction with a Navier-Stokes solver using a blade element method for the calculation of power and wake development. Blades have been replaced with thin surfaces, and a boundary condition of “pressure discontinuity” has been applied with rotor inflow and blade-section characteristics. The proposed improvement consists of applying tangential body forces along the chord, in addition to normal body forces resulting from pressure discontinuity along the blade cross-section. The proposed model has been validated for the flow around a horizontal-axis wind turbine. The results obtained from the proposed model are compared with the experimental results obtained from PIV-wind tunnel techniques. The comparison has displayed the necessity of the proposed model for accurate reproduction of the wake behind rotor. The rapidity of calculation, in comparison to full-geometry modelling, appears to be promising for wind farm simulations.Un modèle amélioré de surface active est proposé pour représenter l’écoulement autour d'une éolienne. Ce modèle est développé en association avec un solveur Navier-Stokes et en utilisant une méthode d'élément de pale pour le calcul de la puissance de l’éolienne et du développement du sillage. Les pales sont remplacées par des surfaces minces, et une condition limite de "discontinuité de pression" a été appliquée à partir de la vitesse d'entrée dans le rotor et des caractéristiques du profil de pale. L'amélioration proposée consiste à appliquer des forces volumiques tangentielles le long de la corde, en plus des forces volumiques normales résultantes de la discontinuité de pression à travers la surface de la pale. Le modèle proposé a été validé pour l'écoulement autour d'une éolienne à axe horizontal. Les résultats obtenus à partir du modèle proposé sont comparés avec les résultats expérimentaux obtenus en soufflerie par la technique PIV. La comparaison a démontré l’intérêt du modèle proposé pour une bonne reproduction du sillage derrière le rotor. La rapidité de calcul, par rapport à la simulation d’une géométrie complète des pales, semble promettant pour des simulations de parcs éoliens.Recherche financée par le laboratoire et par l'Institut CARNOT ART