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Weighted Sparse Image Classification Based on Low Rank Representation
Get PDFThe conventional sparse representation-based image classification usually codes the samples independently, which will ignore the correlation information existed in the data. Hence, if we can explore the correlation information hidden in the data, the classification result will be improved significantly. To this end, in this paper, a novel weighted supervised spare coding method is proposed to address the image classification problem. The proposed method firstly explores the structural information sufficiently hidden in the data based on the low rank representation. And then, it introduced the extracted structural information to a novel weighted sparse representation model to code the samples in a supervised way. Experimental results show that the proposed method is superiority to many conventional image classification methods
Efficient Secure Data Provenance Scheme in Multimedia Outsourcing and Sharing
Get PDFTo cope with privacy leakage caused by multimedia outsourcing and sharing, data provenance is used to analyze leaked multimedia and provide reactive accountability. Existing schemes of multimedia provenance are based on watermarking protocols. In an outsourcing scenario, existing schemes face two severe challenges: 1) when data leakage occurs, there exists a probability that data provenance results can be repudiated, in which case data provenance tracking fails; and 2) when outsourced data are shared, data encryption transfer causes key management burden outside the schemes, and privacy leakage threatens users. In this paper, we propose a novel data provenance scheme with an improved LUT-based fingerprinting protocol, which integrates an asymmetric watermarking protocol, robust watermark algorithm and homomorphic encryption and digital signatures to achieve full non-repudiation provenance. We build an in-scheme stream cipher to protect outsourced multimedia data from privacy leakage and complicated key management. Our scheme is also lightweight and easy to deploy. Extensive security and performance analysis compares our scheme with the state of the art. The results show that our scheme has not only better provenance security and data confidentiality but also higher efficiency for multimedia outsourcing, sharing and provenance
Molecular Beam Epitaxial Growth and Device Characterization of AlGaN Nanowire Ultraviolet-B Light-Emitting Diodes
Get PDFWe report on the design and fabrication of high performance AlxGa1−xN nanowire ultraviolet (UV) light-emitting diodes (LEDs) on silicon substrate by molecular beam epitaxy. The emission wavelength and surface morphology of nanowires can be controlled by varying the growth parameters that include substrate temperatures and/or Aluminum/Gallium flux ratios. The devices exhibit excellent current-voltage characteristics with relatively low resistance. Such nanowire LEDs generate strong emission in the UV-B band tuning from 290 nm to 330 nm. The electroluminescence spectra show virtually invariant blue-shift under injection current from 50 mA to 400 mA, suggesting the presence of a negligible quantum-confined Stark effect. Moreover, we have shown that, the AlGaN nanowire LEDs using periodic structures, can achieve high light extraction efficiency of ~ 89% and 92% for emissions at 290nm and 320nm, respectively. The randomly arranged nanowire 290 nm UV LEDs exhibit light extraction efficiency of ~ 56% which is higher compared to current AlGaN based thin-film UV LEDs
Sustainable Materials Based on Cellulose from Food Sector Agro-Wastes
No full textBiopolymers exhibit unique properties and can be produced from plants’ and crops’ wastes. Cellulose has been used for the production of sustainable materials, nevertheless due to the difficulty inherent to its extraction, several methods have been studied in order to optimize the process. Therefore, this paper reports the extraction of natural polymers from food sector agro-food wastes, including cellulose, following a green chemistry aproach. The cellulose extracted from pumpkin peel was acetylated and dispersed in a polylactic acid (PLA) matrix. The developed materials were characterized in terms of their structure, morphology and thermal stability. The results demonstrated the efficient chemical modification of cellulose and confirmed its good dispersion within the PLA matrix
Mechanism Based Pharmacokinetic Pharmacodynamic Modeling of Vildagliptin as an Add-on to Metformin for Subjects with Type 2 Diabetes
No full textVarious drugs are used to maintain normoglycemia in subjects with type 2 diabetes mellitus. The combination of the drugs from different classes in one single tablet may enhance the effectiveness of the anti-diabetic drugs. To investigate the impact of combining drugs on the glucose regulation of subjects with type 2 diabetes, we propose a pharmacokinetic/pharmacodynamics (PK/PD) mathematical modeling approach for a combination of metformin and vildagliptin drugs. In the proposed modeling approach, two separate PK models representing oral administration of metformin and vildagliptin for diabetic subjects are interconnected to a PD model comprising a detailed compartmental physiological model representing the regulatory effect of insulin, incretins and glucagon hormones on glucose concentration in a human body. The impact of doses of individual drugs and their combination on the blood glucose concentration of a group of type 2 diabetic subjects is investigated. It is indicated that while administration of individual drugs reduces the blood glucose levels, since they have separate mechanisms of action, combining them synergizes lowering the blood glucose levels
Subdivision of Uniform ωB-Spline Curves and Two Proofs of Its Ck−2-Continuity
No full textωB-splines have many optimal properties and can reproduce plentiful commonly-used analytical curves. In this paper, we further propose a non-stationary subdivision method of hierarchically and efficiently generating ωB-spline curves of arbitrary order of ωB-spline curves and prove its Ck−2-continuity by two kinds of methods. The first method directly prove that the sequence of control polygons of subdivision of order k converges to a Ck−2-continuousωB-spline curve of order k. The second one is based on the theories upon subdivision masks and asymptotic equivalence etc., which is more convenient to be further extended to the case of surface subdivision. And the problem of approximation order of this non-stationary subdivision scheme is also discussed. Then a uniform ωB-spline curve has both perfect mathematical representation and efficient generation method, which will benefit the application of ωB-splines
Complex Modal Analysis for the Time-Variant Dynamical Problem of Rotating Pipe Conveying Fluid
No full textA semi-analytical form of complex modal analysis is proposed for the time-variant dynamical problem of rotating pipe conveying fluid system. The complex mode superposition method is introduced for the dynamic analysis in the time and frequency domains, in which appropriate orthogonality conditions are constructed to decouple the time-variant equation of motion. Consequently, complex frequencies and modes of vibration are analytically formulated and the variations of frequencies and damping of the system are evaluated. Numerical time-variant example of rotating pipe conveying fluid illustrates the effectiveness and accuracy of this method. Furthermore, the proposed solution scheme is also applicable to other similar time-variant dynamical problems
Theory and Calculation of the J-Integral for Coupled Chemo-Mechanical Fracture Mechanics
No full textIn this paper, by introducing a chemical field, the J-integral formulation is presented for the chemo-mechanical coupled medium based on the laws of thermodynamics. A finite element implementation of the J-integral was performed to study the mode I chemo-mechanical coupled fracture problem. For derivation of the coupled J-integral, the equivalent domain integral (EDI) method was applied to obtain the mode I J-integral, with expression of the area integrals based on constitutive relationships of a linear elastic small deformation for chemo-mechanical coupling, instead of the finite deformation problem. A finite element procedure is developed to compute the mode I J-integral, and numerical simulation of the y-direction stress field is studied by a subroutine UEL (User defined element) developed in ABAQUS software. Accuracy of the numerical results obtained using the mode I J-integral was verified by comparing them to a well-established model based on linear elastic fracture mechanics (LEFM). Furthermore, a numerical example was presented to illustrate path-independence of the formulated J-integral for a chemo-mechanical coupled specimen under different boundary conditions, showing a high accuracy and reliability of the present method. The variation laws of J-integral and the y-direction stress field with external chemical, mechanical loading and time are revealed. The J-integral value increases with larger external concentration loading in the same integral domain. The extent of diffusion is much greater with larger concentration, which leads to a stronger coupling effect due to the chemical field. This work provides new insights into the fracture mechanics for the chemo-mechanical coupled medium
Time Optimization of Multiple Knowledge Transfers in the Big Data Environment
Get PDFIn the big data environment, enterprises must constantly assimilate big data knowledge and private knowledge by multiple knowledge transfers to maintain their competitive advantage. The optimal time of knowledge transfer is one of the most important aspects to improve knowledge transfer efficiency. Based on the analysis of the complex characteristics of knowledge transfer in the big data environment, multiple knowledge transfers can be divided into two categories. One is the simultaneous transfer of various types of knowledge, and the other one is multiple knowledge transfers at different time points. Taking into consideration the influential factors, such as the knowledge type, knowledge structure, knowledge absorptive capacity, knowledge update rate, discount rate, market share, profit contributions of each type of knowledge, transfer costs, product life cycle and so on, time optimization models of multiple knowledge transfers in the big data environment are presented by maximizing the total discounted expected profits (DEPs) of an enterprise. Some simulation experiments have been performed to verify the validity of the models, and the models can help enterprises determine the optimal time of multiple knowledge transfer in the big data environment
Defining Embedding Distortion for Intra Prediction Mode-Based Video Steganography
Get PDFIn this paper, an effective intra prediction mode-based video strganography is proposed. Secret messages are embedded during the intra prediction of the video encoding without causing large embedding impact. The influence on the sum of absolute difference (SAD) in intra prediction modes (IPMs) reversion phenomenon is sharp when modifying IPMs. It inspires us to take the SAD prediction deviation (SPD) to define the distortion function. What is more, the mapping rule between IPMs and the codewords is introduced to further reduce the SPD values of each intra block. Syndrome-trellis code (STC) is used as the practical embedding implementation. Experimental results demonstrate that our proposed steganographic scheme presents high undetectability compared with existing IPMs-based steganographic approaches. It also outperforms these schemes on stego video quality