1,227 research outputs found
Application of image editing software for forensic detection of image
The image editing software’s available today is apt for creating visually compelling and sophisticated fake images, which causes major issues to the reliability of digital contents as a right representation of reality. Authenticity is the main problem in most digital image communication. Various forensic techniques have been developed for the verification of image integrity, authentication, and tampering detection. Digital image forensics aims at finding the authenticity of images by recovering history of the image. Image manipulations occur at the time of compression, which means changing the DCT coefficients. Forensic technique is capable of detecting chains of operators that is applied to an image. Here the union of Joint Photographic Experts Group compression and full-frame linear filtering were studied and derived an accurate mathematical framework for fully characterizing the probabilistic distributions of the discrete cosine transform (DCT) coefficients of the image, which gets quantized and filtered. This statistical model is used for deriving a set of significant features from the DCT histogram of the input image; these features were fed to a effective classifier which effectively classifies different combinations of linear filtering and compression.Keywords: Full- frame linear filtering, JPEG compression, Linear classifier, image forensic
Reduced cost photonic instantaneous frequency measurement system
A wideband photonic instantaneous frequency measurement system is proposed and practically demonstrated. This system employs only a low-frequency inexpensive photodetector and thus the system cost is reduced
RF photonic instantaneous frequency measurement using DC photo-detection
A microwave photonic instantaneous frequency measurement (IFM) system based on a photonic transversal approach and DC-detection is proposed and practically demonstrated. This system is able to measure the RF frequency and power level independently
Two output RF hybrid coupler using photonic transversal approach
A novel technique to implement a two output broad band RF hybrid coupler based on transversal signal processing is proposed and practically demonstrated. It features broadband frequency range, stable phase difference at outputs, 50 ohm input/output impedance, and low noise characteristics. This technique is suitable for non-coherent optic implementation
Photonic instantaneous frequency measurement using non-linear optical mixing
In this paper we propose and demonstrate a photonically implemented instantaneous frequency measurement system. This system uses two differentially delayed modulated optical carriers that are mixed using a semiconductor optical amplifier. The output of the system includes a DC component that varies as a function of frequency. This can be used for frequency measurement using a low-cost DC photo-detector. Operation is demonstrated from 2-20 GHz
Amplitude independent RF instantaneous frequency measurement system using photonic Hilbert transform
A photonic instantaneous frequency measurement system capable of measuring both RF frequency and power simultaneously, is conceived and practically demonstrated. This system employs an RF photonic Hilbert transformer together with low-cost, low-frequency photo-detectors to obtain two orthogonal DC measurements. This system exhibits a frequency range of 1-10 GHz. Wider frequency range can be achieved through integration
Wideband RF photonic in-phase and quadrature-phase generation
A photonic implementation of a practical broadband RF Hilbert transformer is demonstrated by using a four-tap transversal system. An almost ideal 90° phase shift with less than 3 dB of amplitude ripple has been achieved from 2.4 to 17.6 GHz. An efficient method to realize both transformed (quadrature-phase) and reference (in-phase) signal has been achieved by using a coarse wavelength division multiplexing coupler. Extension of the transformer bandwidth and further improvements of its implementation are discussed
Patients and Health Professionals Views on Caring in Diabetes Disease
Background: Diabetes is a common problem with severe complications. The control of diabetes needs a close and honest relationship between patients and health professionals. The views of these two groups might influence the professional relationship.
Objectives: The purpose of this study was to identify the views of diabetic patients versus the views of diabetic care professionals on the content of caring.
Patients and Methods: This qualitative study was conducted with the content analysis method. The participants consisted of adults who had suffered from diabetes for a minimum of one year, and health care professionals working in diabetes care centers. Fifteen patients and fifteen health professionals participated in the interviews.
Results: The findings present four main themes which are as follows: what caring is and what means to care, the obstacles in providing care, the outcomes of caring, and specialist community-based care as a crucial intervention in diabetes care, the themes were identified and based on the data analysis, It appeared that patients were more outcome centered, while health professionals were more process- centered in the context of caring.
Conclusions: It appeared that patients were more outcome centered, while health professionals were more process -centered in the context of caring
Hydrodynamic instabilities in gaseous detonations: comparison of Euler, Navier–Stokes, and large-eddy simulation
A large-eddy simulation is conducted to investigate the transient structure of an unstable detonation wave in two dimensions and the evolution of intrinsic hydrodynamic instabilities. The dependency of the detonation structure on the grid resolution is investigated, and the structures obtained by large-eddy simulation are compared with the predictions from solving the Euler and Navier–Stokes equations directly. The results indicate that to predict irregular detonation structures in agreement with experimental observations the vorticity generation and dissipation in small scale structures should be taken into account. Thus, large-eddy simulation with high grid resolution is required. In a low grid resolution scenario, in which numerical diffusion dominates, the structures obtained by solving the Euler or Navier–Stokes equations and large-eddy simulation are qualitatively similar. When high grid resolution is employed, the detonation structures obtained by solving the Euler or Navier–Stokes equations directly are roughly similar yet equally in disagreement with the experimental results. For high grid resolution, only the large-eddy simulation predicts detonation substructures correctly, a fact that is attributed to the increased dissipation provided by the subgrid scale model. Specific to the investigated configuration, major differences are observed in the occurrence of unreacted gas pockets in the high-resolution Euler and Navier–Stokes computations, which appear to be fully combusted when large-eddy simulation is employed
Low-cost RF frequency measurement using photonic approach
A technique to implement frequency measurement photonically using only low-cost DC photodetectors is proposed and a proof of concept implementation is practically demonstrated. Techniques to further reduce cost and extend bandwidth are proposed
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