Modeling and simulation of liquid diffusion through a porous finitely elastic solid

A new theory is proposed for the continuum modeling of liquid flow through a porous elastic solid. The solid and the voids are assumed to jointly constitute the macroscopic solid phase, while the liquid volume fraction is included as a separate state variable. A finite element implementation is employed to assess the predictive capacity of the proposed theory, with particular emphasis on the mechanical response of $\text{ Nafion}^{\textregistered }$ membranes to the flow of water.     

The role of nanofillers on the degradation behavior of polylactic acid

This study examines the effect of type and content of various nanofillers on the aging behavior of polylactic acid (PLA)/nanocomposites compared with that of pristine PLA, under specific environmental conditions, namely 80% relative humidity, 40°C temperature, and exposure time up to 6 months. Two different types of nanosized fillers (silica and montmorillonite, MMT) at three different weight fractions as well their mixtures were used for this purpose. The role of the various nanofillers on the aging of pristine PLA and its nanocomposites was investigated in terms of several experimental techniques including Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA), and tensile testing. All studied samples, except those of PLA/MMT/Si nanocomposites, exhibited the same trend in properties during aging. In particular, no significant changes are noted after 1 month of aging. The materials after 3 months of aging experienced a dramatic lowering of the stress–strain curve, whereas at 6 months a reverse effect was observed. Comparing the effect of nanofiller types on the degradation, one could conclude that PLA/MMT nanocomposites exhibit a more homogeneous degradation effect, having a higher impact on yield stress in comparison with silica. In contrast, silica has a greater effect in Young's modulus and strain at break, compared with MMT. The peculiar behavior of the PLA/MMT/Si nanocomposites during aging is explained by the hindering action of the mixture of the two nanofillers on the molecular reordering of the PLA chains in the amorphous region. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers     

Evaluation of cotton seed cake as a feed ingredient for fattening sheep

The value of cotton seed cake as a source of crude protein in sheep diets was studied. The cotton seed cake was incorporated into diets at levels of 0, 15 and 30% after replacement of soya bean meal and was fed ad libitum to growing lambs. The diets were formulated to be isonitrogenous and isocaloric. Sixteen lambs (8 male and 8 female) having an average liveweight of approximately 13.6 kg were used in each treatment. After being fed for 62 days and having reached a liveweight of approximately 26.7 kg, five male lambs from each treatment were slaughtered and carcass data were collected. Results of the growth trial showed that there were no significant differences in feedlot performance or carcass analysis among the lambs fed these diets. The dressing percentage was slightly higher (P > 0.05) for lambs fed the 15% cotton seed cake compared with the 30% cotton seed cake and control diets. However, the final weights were substantially higher (P < 0.001) and live average daily gains and feed intakes were all higher (P < 0.10) for male animals. It was concluded that cotton seed cake is an acceptable feed ingredient for growing sheep and can satisfactorily replace soya bean meal as a source of protein in ruminant diets, a feedstuff locally produced in Greece and substantially cheaper than the imported soya bean meal.     

Comparative study of PLA nanocomposites reinforced with clay and silica nanofillers and their mixtures

This study compares the effects of two different types of nanosized fillers (silica and montmorillonite) at three different weight fractions as well their mixtures on the thermomechanical properties of polylactide (PLA). The role of aggregation and interphase was investigated in terms of several experimental techniques, including scanning electron microscopy, wide‐angle X‐ray scattering (WAXS), thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis (DMA), and tensile measurements. The experimental results clearly suggest that silica and montmorillonite have different reinforcing and toughening effects on PLA, while the combination of the two different nanofillers has a detrimental effect on the tensile properties of the material. Four micromechanics models describing the Young's modulus of the nanocomposites were used to study the different matrix–nanofiller interactions. The best fit of the experimental results was obtained with a model that assumes the presence of an interphase surrounding each nanoparticle. The increase of the nanofiller content above a certain amount was not accompanied by a corresponding increase of the interphase, because the total nanofiller surface area was counterbalanced by the creation of aggregates. It is postulated that the aggregation effect acts antagonistically to the interphase effect. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Case Studies and Information Technology in Civil Engineering Learning

A multimedia-supported case study is presented that deals with a large-scale civil engineering project. This case study is based on the complete analysis, design, and construction files of the developer of the project. The multimedia instructional tool has integrated different disciplines and input from the project manager, senior students, and instructors of different disciplines. This multimedia tool includes hypertext links to modular and stratified information. Information is made available through the user's control in a logical, interactive, deductive, and disciplinary way that follows the flow of a civil engineering project. Text, graphics, and videos are included. The multimedia tool presents a teaching tool that enables senior class civil engineering students to learn about planning, design, and construction phases of a civil engineering project, as well as their integration. The in-class use of the tool and project discussions help the students to relate better their previous academic knowledge to “real-life” problems, enhance their creativity, and increase the level of retention of the new knowledge acquired. Future enhancements and learning possibilities are discussed with the use of additional capabilities of information technology. The multimedia application developed has been used in an academic environment; however, with some modifications, it could be used to improve the “learning curve” of new employees in a company environment.     

The use of accounting information systems in the evaluation of environmental costs: a cost–benefit analysis model proposal

The increasing pressures in the environment and the environmental social awareness have produced the need for studying interactions between the sectors of the economy and the environment. For a more comprehensive evaluation of sustainability and growth, the field of financial accounting needs to be expanded in order to comprise the use of natural resources and losses in the production process. The paper examines and proposes the cost–benefit analysis model as a useful estimation method of environmental revenues and costs incurred in Greece. These revenues and costs will appear in the profit and loss account statement. Environmental tax is an important cost for all industries with sustainable growth. Taxes are imposed on the natural units, which have a determined negative effect on the environment. Moreover, this paper examines the inherent interaction between the environment and the economic performance of enterprises by adopting environmental management and information green accounting systems. Copyright © 2006 John Wiley & Sons, Ltd.     

Testing Separability of Functional Time Series

We derive and study a significance test for determining whether a panel of functional time series is separable. In the context of this paper, separability means that the covariance structure factors into the product of two functions, one depending only on time and the other depending only on the coordinates of the panel. Separability is a property that can dramatically improve computational efficiency by substantially reducing model complexity. It is especially useful for functional data, as it implies that the functional principal components are the same for each member of the panel. However, such an assumption must be verified before proceeding with further inference. Our approach is based on functional norm differences and provides a test with well‐controlled size and high power. We establish our procedure quite generally, allowing one to test separability of autocovariances as well. In addition to an asymptotic justification, our methodology is validated by a simulation study. It is applied to functional panels of particulate pollution and stock market data.     

Computer-mediated communication in computer-assisted language learning: implications for culture-centered design

This study explores the research development pertaining to computer-mediated communication (CMC) in the field of computer-assisted language learning (CALL). The basic premise of this study is that language and consequently communication are essential elements of culture; thus, deep understanding of the role of technology in facilitating communication in online environments can deepen our understanding of the notion of culture and contribute to the specification of a universal design approach in culture-centered design. The authors applied a six-stage approach for conducting a systematic review of the research development in CALL between January 2009 and September 2010. This approach resulted in the development of the CALL map which consisted of 11 themes with which CALL researchers are concerned. This study focuses on CMC, a category which maintains its popularity for more than a decade, thus sustaining itself as a major area in the field. The review brings to the forefront key themes and findings of research in these areas, as well as core concepts emerging from the literature. The study discusses empirical findings and delineates how CMC can enhance language learning, concluding with possible future directions and implications for research and practice.     

Emotion Analysis and Classification: Understanding the Performers' Emotions Using the LMA Entities

The increasing availability of large motion databases, in addition to advancements in motion synthesis, has made motion indexing and classification essential for better motion composition. However, in order to achieve good connectivity in motion graphs, it is important to understand human behaviour; human movement though is complex and difficult to completely describe. In this paper, we investigate the similarities between various emotional states with regards to the arousal and valence of the Russell's circumplex model. We use a variety of features that encode, in addition to the raw geometry, stylistic characteristics of motion based on Laban Movement Analysis (LMA). Motion capture data from acted dance performances were used for training and classification purposes. The experimental results show that the proposed features can partially extract the LMA components, providing a representative space for indexing and classification of dance movements with regards to the emotion. This work contributes to the understanding of human behaviour and actions, providing insights on how people express emotional states using their body, while the proposed features can be used as complement to the standard motion similarity, synthesis and classification methods.     

Empirical Research in Mid-Air Interaction: A Systematic Review

ABSTRACT

Mid-air interaction is a distinct style of natural HCI (Human-Computer Interaction). In mid-air interaction, users make use of their whole body—with a strong focus on hands—and apply gestures, postures, and movements to interact with digital content on distant displays or remote devices. Although the idea of exploiting body movements and gestures in HCI is not new, mid-air interaction is now possible due to the availability of reasonably priced depth cameras and sensors. This article presents a systematic review of empirical research in mid-air interaction, based on a corpus of 104 publications from 2011 to 2018. The review includes: (a) a retrospective on mid-air interaction, which outlines its historical development and clarifications on important concepts; (b) current application domains of mid-air interaction; (c) user requirements methods, focusing on gesture elicitation studies; (d) dimensions of prototyping and design; (e) empirical evaluation methods and issues; (f) a discussion on several trends and challenges for further research and development.