Performance of a Nonwoven Geotextile Reinforced Wall with Unsaturated Fine Backfill Soil

The use of marginal backfills in GSE （geosynthetic stabilized earth） walls has not been recommended by different standards specifications. Restrictions are motivated by the poor hydraulic conductivity of fine soils that are capable of developing of water pressures. However, the use of granular materials can expend the cost of the construction. As a result, local soils, granular or not, have been increasingly used. Unsaturated conditions of fine soils may result in convenient performance even using extensible reinforcements. This paper evaluates the performance of a full scale model of a nonwoven geotextile reinforced wall constructed with fine grained soil backfill. The unsaturated condition was maintained and matric suctions, displacements and reinforcement strains were monitored during the test. Results have shown that the unsaturated condition of the backfill allowed maximum reinforcement peak strain of 0.4 %. For the case of a wrap faced wall on a firm foundation the performance and good agreement between measured strains and factors of safety from limit equilibrium analyses have shown the maintenance of unsaturated conditions as an economical alternative to the use of high quality fill.     

Biofilm formation on different materials for tooth restoration: analysis of surface characteristics

The purpose of this study was to evaluate the effect of roughness parameters and hydrophobicity of restorative material used to restore non-carious cervical lesions on the biofilm formation. Four restorative materials were investigated: conventional glass ionomer cement (KF, Ketac Fill Plus, 3M ESPE), resin-modified glass ionomer cement (VT, Vitremer, 3M ESPE), nanofilled resin-modified glass ionomer cement (KN, Ketac Nano, 3M ESPE), and nanofilled resin composite (FZ, Filtek Z350 XT, 3M ESPE). Forty disk specimens were prepared from each material, dived in four groups. Five samples were used for topography parameters analysis using a 3D profilometry. The amplitude parameters (Sa and Sq), spatial parameter (Sds), and hybrid parameter (Ssc) were extracted in area using cut-off of 0.25 mm. Hydrophobicity was determined by the contact angle measurement of deionized water on the surface. The biofilm collected from a 24-year-old subject was grown on modified brain–heart infusion agar under aerobic conditions at 37 °C for 24 h. Each test disk was immersed in 200 µL of biofilm suspension (n = 10) and incubated for 24 h at 37 °C. Biofilm was evaluated after 24 h formation on each disk after stained with 1 % fluorescein using confocal laser-scanning microscopy. Data were analyzed using one-way ANOVA and Tukey test (α = 0.05), Pearson correlation was used to compare topography parameters with biofilm formation. Significant differences were found in related amplitude parameters (Sa and Sq, FZ = KN > VT > KF). KN presented the highest hydrophobicity. FZ and KN presented the lowest thickness and biovolume of biofilm when compared with VT and KF. All topography parameters were significantly correlated with biofilm formation. FZ and KN, material with nanoparticles presented better performance-related topography parameters and biofilm formation. Clinical relevance: The incorporation of nanotechnology into restorative materials promotes better surface topography with lower biofilm formation.     

Mechanical properties of inclined frictional granular layers

We investigate the mechanical properties of inclined frictional granular layers prepared with different protocols by means of DEM numerical simulations. We perform an orthotropic elastic analysis of the stress response to a localized overload at the layer surface for several substrate tilt angles. The distance to the unjamming transition is controlled by the tilt angle $\alpha $ with respect to the critical angle $\alpha _c$ . We find that the shear modulus of the system decreases with $\alpha $ , but tends to a finite value as $\alpha \rightarrow \alpha _c$ . We also study the behaviour of various microscopic quantities with $\alpha $ , and show in particular the evolution of the contact orientation with respect to the orthotropic axes and that of the distribution of the friction mobilisation at contact.     

Characteristics and organizational constraints of collaborative planning

Inter-departmental co-ordination is considered an important factor for the success of a company. Individuals predominantly plan according to the goals of their own department. In cooperative relationships, however, they also try to create possibilities for the optimization of the planning for the other individual. This paper analyzes the influence of organizational structures on inter-departmental collaborative demand planning. Psychological planning theories were applied to deduce typical collaborative planning requirements. This permitted an evaluation of the quality of inter-departmental planning processes. The following characteristics were identified: communication of anticipated events, knowledge of reference field characteristics, goal agreements, negotiation of alternatives, recognition of planning adequacy, monitoring and error diagnosis, co-ordination of opportunistic planning and finally common reflection and decision process for plan cancellation. For a field study three companies with different demand planning structures were selected. Using the critical incident technique, individuals were asked to describe events in which helping or hindering activities in the intra- and interdepartmental context occurred. These events were analyzed with respect to the derived characteristics of collaborative planning. The results indicated the usefulness of the chosen characteristics for describing crucial aspects of (un)successful collaborative planning. There was tentative evidence also that team-oriented structures including representatives of various departments are more suitable for the management of a high amount of planning uncertainty than department-oriented structures. Furthermore, relationships between organizational design, quality of collaborative planning, logistical performance and satisfaction with inter-departmental communication could be demonstrated.     

Sweet aqueous solution for electrochemical synthesis of polypyrrole: Part 2. On ferrous metals

The electrochemical synthesis of polypyrrole on iron has been fruitfully achieved in aqueous medium of sodium saccharinate and pyrrole. The obtained coating under these conditions has been reached with cyclic voltammetry and chronomethods. The applied current density has a great effect on the thickness of PPy electrodeposited on iron electrodes. The characterization techniques show a good homogeneity of the PPy coating. The corrosion behaviour of PPy/Fe was investigated in sodium chloride by linear polarization, electrochemical impedance spectroscopy, and weight loss. The results show that PPy coating electrodeposited could provide a good protection against corrosion.     

Generating segmented meshes from textured color images

This paper presents a new framework for generating triangular meshes from textured color images. The proposed framework combines a texture classification technique, called W-operator, with Imesh, a method originally conceived to generate simplicial meshes from gray scale images. An extension of W-operators to handle textured color images is proposed, which employs a combination of RGB and HSV channels and Sequential Floating Forward Search guided by mean conditional entropy criterion to extract features from the training data. The W-operator is built into the local error estimation used by Imesh to choose the mesh vertices. Furthermore, the W-operator also enables to assign a label to the triangles during the mesh construction, thus allowing to obtain a segmented mesh at the end of the process. The presented results show that the combination of W-operators with Imesh gives rise to a texture classification-based triangle mesh generation framework that outperforms pixel based methods.     

R&D Activity Selection Process: Building a Strategy-Aligned R&D Portfolio for Government and Nonprofit Organizations

This paper presents a portfolio building process for large public and/or nonprofit research organizations. The proposed approach allocates a research and development (R&D) program budget, taking into consideration both applications and technological areas. It starts with the definition of program objectives and covers the allocation of an R&D program budget, including a final activity selection, according to specific criteria. Budget allocation decisions rely on estimations of risk and return for areas and projects, based on the Markowitz portfolio selection model. A scenario implementation of the proposed portfolio building process in the context of a space agency is included. The application to other areas is also discussed.     

Combining operational flexibility and dependability in FTT-CAN

The traditional approaches to the design of distributed safety-critical systems, due to fault-tolerance reasons, have mostly considered static cyclic table-based traffic scheduling. However, there is a growing demand for operational flexibility and integration, mainly to improve efficiency in the use of system resources, with the network playing a central role to support such properties. This calls for dynamic online traffic scheduling techniques so that dynamic communication requirements are adequately supported. Nevertheless, using dynamic traffic management mechanisms raises additional problems, in terms of fault-tolerance, related with the weaker knowledge of the future system state caused by the higher level of operational flexibility. Such problems have been recently addressed in the scope of using flexible time-triggered CAN (FTT-CAN) in safety-critical applications in order to benefit from the high operational flexibility of this protocol. This paper gathers and reviews the main mechanisms that were developed to provide dependability to the protocol, namely, master replication and fail-silence enforcement.     

Coach planning with opponent models for distributed execution

In multi-agent domains, the generation and coordinated execution of plans in the presence of adversaries is a significant challenge. In our research, a special “coach” agent works with a team of distributed agents. The coach has a global view of the world, but has no actions other than occasionally communicating with the team over a limited bandwidth channel. Our coach is given a set of predefined opponent models which predict future states of the world caused by the opponents’ actions. The coach observes the world state changes resulting from the execution of its team and opponents and selects the best matched opponent model based on its observations. The coach uses the recognized opponent model to predict the behavior of the opponent. Upon opportunities to communicate, the coach generates a plan for the team, using the predictions of the opponent model. The centralized coach generates a plan for distributed execution. We introduce (i) the probabilistic representation and recognition algorithm for the opponent models; (ii) a multi-agent plan representation, Multi-Agent Simple Temporal Networks; and (iii) a plan execution algorithm that allows the robust distributed execution in the presence of noisy perception and actions. The complete approach is implemented in a complex simulated robot soccer environment. We present the contributions as developed in this domain, carefully highlighting their generality along with a series of experiments validating the effectiveness of our coach approach.