LDA Ensembles for Interactive Exploration and Categorization of Behaviors

We define behavior as a set of actions performed by some agent during a period of time. We consider the problem of analyzing a large collection of behaviors by multiple agents, more specifically, identifying typical behaviors as well as spotting behavior anomalies. We propose an approach leveraging topic modeling techniques -- LDA (Latent Dirichlet Allocation) Ensembles -- for representing categories of typical behaviors by topics obtained through applying topic modeling to a behavior collection. When such methods are applied to text documents, the goodness of the extracted topics is usually judged based on the semantic relatedness of the terms pertinent to the topics. This criterion, however, may not be applicable to topics extracted from non-textual data, such as action sets, since relationships between actions may not be obvious. We have developed a suite of visual and interactive techniques supporting the construction of an appropriate combination of topics based on other criteria, such as distinctiveness and coverage of the behavior set. Our case studies in the operation behaviors in the security management system and visiting behaviors in an amusement park and the expert evaluation of the first case study demonstrate the effectiveness of our approach

Cement degradation in CO2 storage sites: a review on potential applications of nanomaterials

© 2018 The Author(s) Carbon capture and sequestration (CCS) has been employed to reduce global warming, which is one of the critical environmental issues gained the attention of scientific and industrial communities worldwide. Once implemented successfully, CCS can store at least 5 billion tons of CO2per year as an effective and technologically safe method. However, there have been a few issues raised in recent years, indicating the potential leakages paths created during and after injection. One of the major issues might be the chemical interaction of supercritical CO2with the cement, which may lead to the partial or total loss of the cement sheath. There have been many approaches presented to improve the physical and mechanical properties of the cement against CO2attack such as changing the water-to-cement ratio, employing pozzolanic materials, and considering non-Portland cements. However, a limited success has been reported to the application of these approaches once implemented in a real-field condition. To date, only a few studies reported the application of nanoparticles as sophisticated additives which can reinforce oil well cements. This paper provides a review on the possible application of nanomaterials in the cement industry where physical and mechanical characteristics of the cement can be modified to have a better resistance against corrosive environments such as CO2storage sites. The results obtained indicated that adding 0.5 wt% of Carbon NanoTubes (CNTs) and NanoGlass Flakes (NGFs) can reinforce the thermal stability and coating characteristics of the cement which are required to increase the chance of survival in a CO2sequestrated site. Nanosilica can also be a good choice and added to the cement by as much as 3.0 wt% to improve pozzolanic reactivity and thermal stability as per the reports of recent studies

Well Technologies for CO

Storing carbon dioxide (CO2) underground is considered the most effective way for long-term safe and low-cost CO2 sequestration. This recent application requires long-term wellbore integrity. A CO2 leakage through the annulus may occur much more rapidly than geologic leakage through the formation rock, leading to economic loss, reduction of CO2 storage efficiency, and potential compromise of the field for storage. The possibility of such leaks raises considerable concern about the long-term wellbore isolation and the durability of hydrated cement that is used to isolate the annulus across the producing/injection intervals in CO2-storage wells. We propose a new experimental procedure and methodology to study reactivity of CO2-Water-Cement systems in simulating the interaction of the set cement with injected supercritical CO2 under downhole conditions. The conditions of experiments are 90°C under 280 bars. The evolution of mechanical, physical and chemical properties of Portland cement with time is studied up to 6 months. The results are compared to equivalent studies on a new CO2-resistant material; the comparison shows significant promise for this new material

Globalization and African Cinema: Distribution and Reception in the Anglophone Region

Globalization is the all-pervasive constituent of contemporary living, especially where it is underwritten by colonial histories. Keyan Tomaselli argues that European interpretive frameworks have determined readings of African texts.1 Globalization needs to be understood through the discourse of capital, to understand how entire societies have become affected economically and socially by the dynamics of diversity in this new international division of labor.2 Globalization is the narrative of socialization that also helps us to locate the local within the global