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Distortion Function for Emoji Image Steganography
Get PDFNowadays, emoji image is widely used in social networks. To achieve covert communication in emoji images, this paper proposes a distortion function for emoji images steganography. The profile of image content, the intra- and inter-frame correlation are taken into account in the proposed distortion function to fit the unique properties of emoji image. The three parts are combined together to measure the risks of detection due to the modification on the cover data. With the popular syndrome trellis coding (STC), the distortion of stego emoji image is minimized using the proposed distortion function. As a result, less detectable artifacts could be found in the stego images. Experimental results show that the proposed distortion function performs much higher undetectability than current state-of-the-art distortion function HILL which is designed for natural image
LRV: A Tool for Academic Text Visualization to Support the Literature Review Process
Get PDFText visualization is concerned with the representation of text in a graphical form to facilitate comprehension of large textual data. Its aim is to improve the ability to understand and utilize the wealth of text-based information available. An essential task in any scientific research is the study and review of previous works in the specified domain, a process that is referred to as the literature survey process. This process involves the identification of prior work and evaluating its relevance to the research question. With the enormous number of published studies available online in digital form, this becomes a cumbersome task for the researcher. This paper presents the design and implementation of a tool that aims to facilitate this process by identifying relevant work and suggesting clusters of articles by conceptual modeling, thus providing different options that enable the researcher to visualize a large number of articles in a graphical easy-to-analyze form. The tool helps the researcher in analyzing and synthesizing the literature and building a conceptual understanding of the designated research area. The evaluation of the tool shows that researchers have found it useful and that it supported the process of relevant work analysis given a specific research question, and 70% of the evaluators of the tool found it very useful
Improved Fully Convolutional Network for Digital Image Region Forgery Detection
Get PDFWith the rapid development of image editing techniques, the image splicing behavior, typically for those that involve copying a portion from one original image into another targeted image, has become one of the most prevalent challenges in our society. The existing algorithms relying on hand-crafted features can be used to detect image splicing but unfortunately lack precise location information of the tampered region. On the basis of changing the classifications of fully convolutional network (FCN), here we proposed an improved FCN that enables locating the spliced region. Specifically, we first insert the original images into the training dataset that contains tampered images forming positive and negative samples and then set the ground truth masks of the original images to be black images. The purpose of forming positive and negative samples is to guide the improved FCN to distinguish the differences between the original images and spliced images. After these steps, we conducted an experiment to verify our proposal, and the results reveal that the improved FCN really can locate the spliced region. In addition, the improved FCN achieves improved performance compared to the already-existing algorithms, thereby providing a feasible approach for digital image region forgery detection
An Improved MDS-MAP Localization Algorithm Based on Weighted Clustering and Heuristic Merging for Anisotropic Wireless Networks with Energy Holes
Get PDFThe MDS-MAP (multidimensional scaling-MAP) localization algorithm utilize almost merely connectivity information, and therefore it is easy to implement in practice of wireless sensor networks (WSNs). Anisotropic networks with energy hole, however, has blind communication spots that cause loss of information in the merging phase of MDSMAP. To enhance the positioning accuracy, the authors propose an MDS-MAP (CH) algorithm which can improve the clustering and merging strategy. In order to balance the effect of energy consumption and the network topology stabilization, we present a weighted clustering scheme, which considers the residual energy, the degree of connectivity nodes and node density. As the original MAD-MAP method poses a limitation of merging condition, the authors relax the merging requirement and present a heuristic estimation method for lost connectivity over energy holes. Simulation results show that the improved MDS-MAP (CH) localization algorithm has achieved higher localization accuracy, better-balanced energy consumption and stronger network robustness
Convergence Properties of Local Defect Correction Algorithm for the Boundary Element Method
No full textSometimes boundary value problems have isolated regions where the solution changes rapidly. Therefore, when solving numerically, one needs a fine grid to capture the high activity. The fine grid can be implemented as a composite coarse-fine grid or as a global fine grid. One cheaper way of obtaining the composite grid solution is the use of the local defect correction technique. The technique is an algorithm that combines a global coarse grid solution and a local fine grid solution in an iterative way to estimate the solution on the corresponding composite grid. The algorithm is relatively new and its convergence properties have not been studied for the boundary element method. In this paper the objective is to determine convergence properties of the algorithm for the boundary element method. First, we formulate the algorithm as a fixed point iterative scheme, which has also not been done before for the boundary element method, and then study the properties of the iteration matrix. Results show that we can always expect convergence. Therefore, the algorithm opens up a real alternative for application in the boundary element method for problems with localised regions of high activity
Effect of Poly(ε-caprolactone-b-tetrahydrofuran) Triblock Copolymer Concentration on Morphological, Thermal and Mechanical Properties of Immiscible PLA/PCL Blends
No full textIn this study a low molecular weight triblock copolymer derived from ε-caprolactone and tetrahydrofuran was used as a non-reactive compatibilizer of immiscible PLA/PCL blends. Ternary blends with 0, 1.5 wt%, 3 wt% and 5 wt% copolymer and about 75 wt% PLA were prepared by single screw extrusion and characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), tensile and Izod impact testing. SEM micrographs showed that the size of the dispersed PCL domains was practically constant regardless of copolymer concentration. This result can be explained by the low shear rate employed during processing step and a decrease of PCL viscosity by presence of the triblock copolymer. However, when the copolymer concentration increased, strain at break of PLA/PCL blends also increased. PLA/PCL blend with 0 wt% copolymer presented 2% strain at break, whereas PLA/PCL blend with 5 wt% copolymer exhibited 90%
Conversion of Waste Parasitic Insect (<i>Hylobius abietis</i> L.) into Antioxidative, Antimicrobial and Biodegradable Films
No full textHylobius abietis is a plant parasitic insect belonging to the order Coleoptera and which causes severe damages to coniferous forests in Northern and Eastern Europe. This current study is aimed to provide a new viewpoint into the waste of this insect by producing chitosan. Dry insect corpses consisted of 27.9% chitin and 86.2% of the chitin was converted into the chitosan. FT-IR spectra analyses confirmed the purity and the deacetylation degree of the produced chitosan (molecular weight of chitosan; 7.3 kDa). This chitosan exhibited antimicrobial activity against 18 bacterial strains. Further, biodegradable chitosan composite films with β-carotene were produced. Antioxidant activity of chitosan films were found to be higher than chitosan gels; and β-carotene incorporation further increased the antioxidative properties of the chitosan films. This study demonstrated that the waste of parasitic insect like H. abietis can be evaluated as a source for production of biodegradable and edible chitosan-based films for applications in food coating
Glucose-Biobased Non-Isocyanate Polyurethane Rigid Foams
No full textGlucose-based non-isocyanate polyurethanes (NIPU) were prepared by reaction of glucose with dimethyl carbonate and hexamethylene diamine. These were used to prepare partially biobased polyurethane foams by reaction with NaHCO3 as a blowing agent and addition of a silane coupling agent having different functions such as coreactant and adjuvant to obtain more uniform and smaller cells. The foams were foamed and hardened by applying heat. The foams presented very limited fire resistance indicating that as for synthetic polyurethane foams the eventual use of a fire retardant appears to be necessary. The 2 hours water absorption was used to indicate if close cells or open cells occur. More characteristic is their stress strain behaviour. While compression does indeed flatten the cell walls nonetheless the cellular structure is maintained and the cell walls have not been destroyed. This indicates a certain level of elasticity in the cell walls of formulations containing NaHCO3. In effect the macro-appearance of this foams, confirms this explanation as the foam is densified and holds together
Biodegradable Additive for the Construction Industry
No full textThis paper presents the patent of a new additive for the construction industry, which is obtained from the biomass residues of the wood industry. This additive is biodegradable and has fluidifying, foaming, plasticizing and stabilizing properties. When the additive is mixed with cement binder compositions, cement mortar and concrete, lightweight, flame-retardant cellular materials, thermal and acoustic insulators are obtained
Study on Toughening Phenolic Foams in Phosphorus-Containing Tung Oil-Based Derivatives
No full textPhenolic foams (PFs) as thermal insulation material with outstanding flame retardancy are required to match society’s ever expanding safety expectations; however, a trade off exists between flame retardancy and toughness. Here, for the first time, we synthesized a novel reactive phosphorus containing tung oil based derivative and used it to toughen PF, resulting in PFs with a combination of excellent mechanical properties and flame retardancy. Compared with pure PF, the modified PFs exhibit enhanced mechanical properties, with specific compressive and flexural strengths as high as 5.67 MPa and 12.46 MPa, which represent increases of 90.67% and 178.7% over those of pure PF, respectively. Meanwhile, the limiting oxygen index (LOI) values of the modified PFs are improved as much as 40.83%. Scanning electron microscopy micrographs show that the microstructure of the modified PFs is better than that of pure PF, with a more uniform cell morphology, a narrower pore size distribution range, and a smaller average pore size, all of which are beneficial to the foam’s mechanical properties. This study provides a scientific paradigm for the development of advanced PFs based on renewable biological resources