Blind digital watermarking in PDF documents using Spread Transform Dither Modulation

In this paper, a blind digital watermarking scheme for Portable Document Format (PDF) documents is proposed. The proposed method is based on a variant Quantization Index Modulation (QIM) method called Spread Transform Dither Modulation (STDM). Each bit of the secret message is embedded into a group of characters, more specifically in their x-coordinate values. The method exhibits experiments of two opposite objectives: transparency and robustness, and is motivated to present an acceptable distortion value that shows sufficient robustness under high density noises attacks while preserving sufficient transparency.     

Mixed convective heat transfer enhancement in a ventilated cavity by flow modulation via rotating plate

The present study numerically explores the mixed convection phenomena in a differentially heated ventilated square cavity with active flow modulation via a rotating plate. Forced convection flow in the cavity is attained by maintaining external fluid flow through an opening at the bottom of the left cavity wall while leaving it through another opening at the right cavity wall. A counter-clockwise rotating plate at the center of the cavity acts as an active flow modulator. Moving mesh approach is used for the rotation of the plate and the numerical solution is achieved using arbitrary Lagrangian-Eulerian finite element formulation with a quadrilateral discretization scheme. Transient parametric simulations have been performed for various frequency of the rotating plate for a fixed Reynolds number (Re) of 100 based on maximum inlet flow velocity while the Richardson number (Ri) is maintained at unity. Heat transfer performance has been evaluated in terms of spatially averaged Nusselt number and time-averaged Nusselt number along the heated wall. Power spectrum analysis in the frequency domain obtained from the fast Fourier transform analysis indicates that thermal frequency and plate frequency start to deviate from each other at higher values of velocity ratio (>4).     

Influence of bunch maturation and chemical precursors on acrylamide formation in starchy banana chips

The present study investigated the effect of ripening stages and chemical precursors on acrylamide formation in deep-fried chips of five plantains and one cooking banana. The highest level of acrylamide was found in the cooking banana, followed by False Horn plantain and French plantain, respectively. French plantain hybrids exhibited a significantly lower (P < 0.05) level of acrylamide when compared to French plantain. The ripening stage demonstrated a positive Pearson correlation (P < 0.05, r = 0.57) with acrylamide formation. As ripening progressed, the levels of glucose and fructose significantly increased (P < 0.05) and showed a positive correlation with acrylamide formation (r = 0.85 and 0.96, respectively). The level of the amino acid asparagine during ripening was not correlated with acrylamide formation. In contrast, the level of histidine, arginine, iso-leucine and cystine during ripening was positively correlated (P < 0.05, r > 0.60) with acrylamide formation in fried chips. The higher level of TP was significantly related (P < 0.05) to the lower level of acrylamide (r = −0.62). The reduced levels of carotenoid isomers, except lutein, during fruit ripening were positively correlated (P < 0.05) with acrylamide formation, especially trans-BC (r = 0.72) and 9-cis-BC(r = 0.64).     

Solution calorimetry: A novel perspective into the dissolution process of food powders

The enthalpy of dissolution of two food powders, maltodextrin and skim milk, was studied by means of isothermal solution calorimetry. The effects of the moisture content and the physical state of the samples were investigated. A reduced exothermic response was found as the moisture content of the samples increased. It was shown that this effect is reversible upon re-drying of the solid, unless crystallization occurs. In the skim milk powder, crystallization of lactose occurred, leading to a less exothermic response. In addition, the dissolution kinetics of single particles was followed in situ with real time video acquisition and a novel image analysis technique. The data showed a significant effect of the physical state of the powder on the dissolution kinetics. Fully amorphous skim milk powder dissolved significantly faster than the recrystallized counterpart. A clear relation was observed between the physical state of the powders, their thermodynamic response and the dissolution kinetics.     

Similarity based image selection with frame rate adaptation and local event detection in wireless video sensor networks

Wireless Video Sensor Networks (WVSNs7unding environmental information. Those sensor nodes can locally process the information and then wirelessly transmit it to the coordinator and to the sink to be further processed. As a consequence, more abundant video and image data are collected. In such densely deployed networks, the problem of data redundancy arises when information are gathered from neighboring nodes. To overcome this problem, one important enabling technology for WVSN is data aggregation, which is essential to be cost-efficient. In this paper, we propose a new approach for data aggregation in WVSN based on images and shot similarity functions. It is deployed on two levels: the video-sensor node level and the coordinator level. At the sensor node level the proposed algorithms aim at reducing the number of frames sensed by the sensor nodes and sent to the coordinator. At the coordinator level, after receiving shots from different neighbouring sensor nodes, the similarity between these shots is computed to eliminate redundancies and to only send the frames which meet a certain condition to the sink. The similarity between shots is evaluated based on their color, edge and motion information. We evaluate our approach on a live scenario and compare the results with another approach from the literature in terms of data reduction and energy consumption. The results show that the two approaches have a significant data reduction to reduce the energy consumption, thus our approach tends to overcome the other one in terms of reducing the energy consumption related to the sensing process, and to the transmitting process while guaranteeing the detection of all the critical events at the node and the coordinator levels.

     

Magnetron sputtered tungsten oxide films activated by dip-coated platinum for ppm-level hydrogen detection

Platinum-activated tungsten oxide (Pt-WO₃) films are prepared for hydrogen (H₂) sensing applications. In this study, WO₃ films were fabricated by reactive magnetron sputtering and Pt clusters were deposited on them by dip-coating. The microstructure, chemical composition and phase structure of Pt-WO₃ films were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction, respectively. It was observed that a reconditioning period is required after a rest period of the sensor for obtaining a stable signal. A thermal treatment at 450 °C for 24 h is proposed to solve this problem.     

Topology optimization of heat and mass transfer problems in two fluids—one solid domains

Abstract

Among various topology optimization methods used in fluid flow problems, density approach has gained more interest compared to other techniques as level set approach, topological derivative technique, and phase field method. The key part of density approach is the penalized interpolation function, which forces progressively porous cells made of fluid and solid simultaneously to belong discretely to fluid or solid sub-domains. However this type of problem was only solved in mono-fluid domains, in which the method accounts for the distribution of a single fluid and a single solid. The actual work aims to extend topology optimization in fluid flow problems to bi-fluid domain. A new interpolation function was developed for this purpose. Furthermore a penalization function was integrated in the multiobjective function, which ensure that each fluid takes its own path in the device, while maintaining a minimal required solid thickness between the channels of different fluids. The results showed the capacity of the proposed method to deal with multiple fluid phases in minimizing the pressure drop while maximizing heat exchange between different flows. The main conclusion is the potential of density approach to be applied on optimization of heat exchangers.     

Global Analysis of the Dynamics of a Piecewise Linear Vector Field Model for Prostate Cancer Treatment

Oncological therapies usually are applied intermittently, i.e., not continuously over time. In the periods in between, though, the cancer cells are usually left free to grow. This intermittency is a key issue in prostate cancer hormonal therapies based on androgen suppression. Here, we address this treatment modality by analyzing a piecewise smooth vector field approach. In fact, using the PSA (prostate-specific antigen) serum level as a control variable to switch between treatment and no-treatment periods of hormone therapy (androgen withdrawal), by means of typical parameter values, our theoretical analysis supports the idea that intermittent androgen suppression may prevent a prostate cancer relapse for a specific class of patients.

     

Osteocyte staining with rhodamine in osteonecrosis and osteoarthritis of the femoral head

Death of osteocytes is synonymous of bone death. Aseptic osteonecrosis of the femoral head is a lesion characterized by the death of osteocytes occurring after major vascular changes. The evolution may lead to hip osteoarthritis, which requires total hip arthroplasty in most cases. Evolution of aseptic osteonecrosis in four radiological stages is well known. We analyzed 24 femoral heads from patients with osteonecrosis or osteoarthritis, retrieved at the time of surgery for a hip arthroplasty. The aim of the study was to clearly identify the necrotic bone from the living bone in the histological samples. The femoral heads were sawed, and a large sample was harvested in the superior zone; it was stained en‐bloc with rhodamine dissolved in formalin to make the osteocytes fluorescent under UV light microscopy. Undecalcified sections, 7 μm thick, were obtained on a heavy‐duty microtome. A micrographic analysis using two UV excitation wavelengths visualized the living osteocytes (in green) and the bone matrix (in blue). A simple method to prepare combined images is described. In addition, the blocks can be analyzed by confocal microscopy to visualize more details. It is possible to identify at low magnification the osteocytes within the bone matrix and the osteonecrotic areas where osteocytes have disappeared. Identification of osteocytes showed that newly formed bone packets are laid on dead trabeculae in patients with aseptic osteonecrosis or with osteoarthritis. In the osteosclerotic areas, the enlarged trabeculae have a dead central core surrounded by recently apposed bone structure units.