Power-aware agent-solution for information communication in?WSN

The information-communication in an energy efficient and scalable manner in a wireless sensor network is a basic need. In this work, we use the multi-agent approach in order to build an Information Importance Based Communication (IIBC) for large scale wireless sensor network data processing. A multi-agent cooperation can be used to greatly reduce the communication cost, especially over low bandwidth links, by treating data cooperatively in sensor nodes rather than bringing this data to a central processor. The principal goal of our proposition is to maximize the wireless sensor network life time and simultaneously to insure a sufficient level of performance in term of latency, packet loss and reliability. Through successive simulations, IIBC proved its ability to reduce the power consumption of the sensor node to maximize ??the mean time to first network partition?? in several network densities and scales.     

Sparse representations for spatial prediction and texture refinement

In this work, we propose a novel approach for signal prediction based on the use of sparse signal representations and Matching Pursuit (MP) techniques. The paper first focuses on spatial texture prediction in a conventional block-based hybrid coding scheme and secondly addresses inter-layer prediction in a scalable video coding (SVC) framework. For spatial prediction the signal reconstruction of the block to predict is based on basis functions selected with the MP iterative algorithm, to best match a causal neighborhood. Inter-layer MP based prediction employs base layer upsampled components additionally to the causal neighborhood in order to improve the representation of high frequencies. New solutions are proposed for efficiently deriving and exploiting the atoms dictionary through phase refinement and mono-dimensional basis functions. Experimental results indicate noticeable improvement of rate/distortion performance compared to the standard prediction methods as specified in H.264/AVC and its extension SVC.     

Athermal concentration by osmotic evaporation of roselle extract, apple and grape juices and impact on quality

Osmotic evaporation (or osmotic distillation) was carried out on roselle extract, apple and grape juices. The industrial pilot plant used had a hydrophobic, polypropylene, hollow-fiber membrane with an area of 10.2 m² and an average pore diameter of 0.2 μm. It was suitable for concentrating vegetable extracts and fruit juices, and controlled various parameters such as temperature, flow velocity, and brine concentration. The final total soluble solids (TSS) contents achieved were 660, 570, and 610 g kg⁻¹ for grape juice, apple juice, and roselle extract, respectively. Temperature and concentration of solutions significantly influenced evaporation flux, which, for roselle extract, was 1.5 kg h⁻¹ m⁻² at 610 g TSS kg⁻¹ and 45 °C. The physico-chemical, biochemical, and aromatic qualities of concentrates obtained by osmotic evaporation were much higher than those of thermal concentrates, and close to those of the initial products.

Industrial relevance

Membrane processes are increasingly used to concentrate thermo-sensitive fruit juices and plant extracts. Their capacity to operate at moderate temperatures and pressures means that their energy consumption is low, while they produce good quality concentrates. Nonetheless, the main disadvantage of baromembrane processes is their inability to reach the concentration levels standard for products of thermal evaporation because of limitations resulting from high osmotic pressure. Actually, reverse osmosis membranes and equipment limit the final concentration of fruit juices to about 25–35°Brix. Osmotic evaporation has attracted considerable interest, as it can concentrate juices to as much as 65°Brix. This process, when applied to various juices, better preserves the quality of raw materials. However, because of the geometrical limitations of commercially available membranes and modules, juices must first be clarified. To our knowledge, only a few studies on osmotic evaporation have so far been conducted at a semi-industrial scale and never with roselle extracts.     

Vitamin D intestinal absorption is not a simple passive diffusion: evidences for involvement of cholesterol transporters

Scope : It is assumed that vitamin D is absorbed by passive diffusion. However, since cholecalciferol (vitamin D₃) and cholesterol display similar structures, we hypothesized that common absorption pathways may exist. Methods and results : Cholecalciferol apical transport was first examined in human Caco‐2 and transfected Human embryonic kidney (HEK) cells. Cholecalciferol uptake was then valuated ex vivo and in vivo, using either wild‐type mice, mice overexpressing Scavenger Receptor class B type I (SR‐BI) at the intestinal level or mice treated or not with ezetimibe. Cholecalciferol uptake was concentration‐, temperature‐ and direction‐dependent, and was significantly impaired by a co‐incubation with cholesterol or tocopherol in Caco‐2 cells. Moreover Block Lipid Transport‐1 (SR‐BI inhibitor) and ezetimibe glucuronide (Niemann‐Pick C1 Like 1 inhibitor) significantly decreased cholecalciferol transport. Transfection of HEK cells with SR‐BI, Cluster Determinant 36 and Niemann‐Pick C1 Like 1 significantly enhanced vitamin D uptake, which was significantly decreased by the addition of Block Lipid Transport‐1, sulfo‐N‐succinimidyl oleate (Cluster Determinant 36 inhibitor) or ezetimibe glucuronide, respectively. Similar results were obtained in mouse intestinal explants. In vivo, cholecalciferol uptake in proximal intestinal fragments was 60% higher in mice overexpressing SR‐BI than in wild‐type mice (p<0.05), while ezetimibe effect remained non‐significant. Conclusion: These data show for the first time that vitamin D intestinal absorption is not passive only but involves, at least partly, some cholesterol transporters.     

An intelligent agent-based scheme for vertical handover management across heterogeneous networks

Advances in technology have enabled a proliferation of mobile devices and a broad spectrum of novel and outbreaking solutions for new applications and services. The increasing demand for all time and everywhere services requires the network operators to integrate different kinds of wireless and cellular networks. To enable this integration, it is important that users can roam freely across networks. As different technologies are involved in the current infrastructure, the problem of vertical handover needs to be addressed. To cope with the problem of seamless connectivity, several solutions have been presented. But most of them either lack intelligence or are not adaptable for reducing the packet loss and delay involved in the handover procedure. An intelligent technique is needed in order to perform the service continuity in the heterogeneous environment. This paper presents a cooperative agent based approach for the vertical handover using a knowledge plane. We propose to introduce the agents in the mobile nodes and access points to collect the necessary information from the environment. Based on this information, agents take a handover decision. A selection function is also introduced in this work which helps in choosing a best network from the available ones for handover. Finally, the proposed approach is validated with the help of simulations.     

Stochastic resonance can enhance information transmission in neural networks

Stochastic resonance (SR) is a noise-induced phenomenon whereby signal detection can be improved by the addition of background noise in nonlinear systems. SR can also improve the transmission of information within single neurons. Since information processing in the brain is carried out by neural networks and noise is present throughout the brain, the hypothesis that noise and coupling play an important role in the control of information processing within a population of neurons to control was tested. Using computer simulations, we investigate the effect of noise on the transmission of information in an array of neurons, known as array-enhanced SR (AESR) in an interconnected population of hippocampal neurons. A subthreshold synaptic current (signal) modeled by a filtered homogeneous Poisson process was applied to a distal position in each of the apical dendrites, while background synaptic signals (uncorrelated noise) were presented to the midpoint in the basal dendrite. The transmembrane potentials were recorded in each cell of an array of CA1 neuron models, in order to determine spike firing times and to estimate the total and noise entropies from the spike firing times. The results show that the mutual information is maximized for a specific amplitude of uncorrelated noise, implying the presence of AESR. The results also show that the maximum mutual information increases with increased numbers of neurons and the strength of connections. Moreover, the relative levels of excitation and inhibition modulate the mutual information transfer. It is concluded that uncorrelated noise can enhance information transmission of subthreshold synaptic input currents in a population of hippocampal CA1 neuron models. Therefore, endogenous neural noise could play an important role in neural tissue by modulating the transfer of information across the network.     

Wavelet shrinkage: unification of basic thresholding functions and thresholds

This work addresses the unification of some basic functions and thresholds used in non-parametric estimation of signals by shrinkage in the wavelet domain. The soft and hard thresholding functions are presented as degenerate smooth sigmoid-based shrinkage functions. The shrinkage achieved by this new family of sigmoid-based functions is then shown to be equivalent to a regularization of wavelet coefficients associated with a class of penalty functions. Some sigmoid-based penalty functions are calculated, and their properties are discussed. The unification also concerns the universal and the minimax thresholds used to calibrate standard soft and hard thresholding functions: these thresholds pertain to a wide class of thresholds, called the detection thresholds. These thresholds depend on two parameters describing the sparsity degree for the wavelet representation of a signal. It is also shown that the non-degenerate sigmoid shrinkage adjusted with the new detection thresholds is as performant as the best up-to-date parametric and computationally expensive method. This justifies the relevance of sigmoid shrinkage for noise reduction in large databases or large size images.     

Modeling the atmospheric transport and deposition of PCDD/F to the Great Lakes

Atmospheric deposition is a significant loading pathway for polychlorinated dibenzo-p-dioxins and dibenzofurans (dioxin) to the Great Lakes. An innovative approach using NOAA's HYSPLIT atmospheric fate and transport model was developed to estimate the 1996 dioxin contribution to each lake from each of 5,700 point sources and 42,600 area sources in a U.S./Canadian air emissions inventory. These unusually detailed source-receptor modeling results show that deposition to each lake arises from a broad geographical region, with significant contributions from up to 2,000 km away. The source categories contributing most significantly to 1996 dioxin deposition appear to be municipal waste incineration, iron sintering, medical waste incineration, and cement kilns burning hazardous waste. Model-predicted air concentrations and deposition fluxes were consistent with ambient measurement data, within the uncertainties in each, but there may be a moderate tendency toward underestimation using midrange emissions estimates. The most likely reason for this tendency appears to be missing or underestimated emissions sources, but in-situ atmospheric formation of octachlorinated dibenzo-p-dioxin (OCDD) and heptachlorinated dibenzo-p-dioxin (HpCDD) may have also contributed. Despite uncertainties, the findings regarding the relative importance of different sources types and source regions appear to be relatively robust and may be useful in prioritizing pollution prevention efforts.     

Comparison of high voltage and high temperature performances of wide bandgap semiconductors for vertical power devices

Temperature dependent properties of wide bandgap semiconductors have been used to calculate theoretical specific on-resistance, breakdown voltage, and thermal run-away temperature in SiC, GaN, diamond, and Si vertical power devices for comparison. It appears mainly that diamond is interesting for high power devices for high temperature applications. At room temperature, diamond power devices should be superior to SiC only for voltage higher than 30–40 kV, due to the high energy activation of the dopants.