Showing papers in "Optik in 2015"
TL;DR: The experimental results show that low exposure image enhancement problem, which was not addressed by earlier HE based methods, has been efficiently handled by these new methods.
Abstract: This paper proposes two exposure based recursive histogram equalization methods for image enhancement. The proposed methods are very effective for images acquired in low light condition like underwater sequences or night vision images. The first method is recursive exposure based sub-image histogram equalization (R-ESIHE) that recursively performs ESIHE [20] method till the exposure residue among successive iteration is less than a predefined threshold. The second method is named as recursively separated exposure based sub image histogram equalization (RS-ESIHE) that performs the separation of image histogram recursively; separate each new histogram further based on their respective exposure thresholds and equalize each sub histogram individually. The experimental results show that low exposure image enhancement problem was not addressed by earlier HE based methods, has been efficiently handled by these new methods. The performance evaluation of new methods is done in terms of image information content as well as visual quality inspection. The proposed methods outperforms earlier HE based contrast enhancement algorithms specifically for low light images.
119 citations
TL;DR: In this article, the design of all optical logic gates based on two-dimensional photonic crystal (PhC) composed of triangular lattice of air holes in silicon (Si) was reported.
Abstract: In this paper, we report the design of all optical logic gates based on two-dimensional photonic crystal (PhC) composed of triangular lattice of air holes in silicon (Si). The proposed structure has been simulated using finite difference time domain (FDTD) method and it has been shown that all optical logic operations can be achieved if an appropriate initial phase is introduced between the input beams so that they may interfere constructively or destructively. The optical logic gates designed in the proposed structure have a response period of 1.024 ps and can operate at a bit rate of 0.976 Tbit/s.
111 citations
TL;DR: Compared with classic particle swarm optimization K-means clustering algorithm (PSOK), DPSOK algorithm has obvious superiority in improving image segmentation quality and efficiency.
Abstract: K-means clustering is usually used in image segmentation due to its simplicity and rapidity. However, K-means is heavily dependent on the initial number of clusters and easily falls into local falls into local optimum. As a result, it is often difficult to obtain satisfactory visual effects. As an evolutionary computation technique, particle swarm optimization (PSO) has good global optimization capability. Combined with PSO, K-means clustering can enhance its global optimization capability. But PSO also has the shortcoming of easily falling into local optima. This study proposes a new image segmentation algorithm called dynamic particle swarm optimization and K-means clustering algorithm (DPSOK), which is based on dynamic particle swarm optimization (DPSO) and K-means clustering. The calculation methods of its inertia weight and learning factors have been improved to ensure DPSOK algorithm keeping an equilibrium optimization capability. Experimental results show that DPSOK algorithm can effectively improve the global search capability of K-means clustering. It has much better visual effect than K-means clustering in image segmentation. Compared with classic particle swarm optimization K-means clustering algorithm (PSOK), DPSOK algorithm has obvious superiority in improving image segmentation quality and efficiency.
100 citations
TL;DR: In this paper, structural and optical properties of as-prepared and annealed thermal evaporated CdTe films were investigated, and the results confirm the films nanostructure property.
Abstract: Structural and optical properties of as-prepared and annealed thermal evaporated CdTe films were investigated. The annealing temperature (373–523 K) affects both structural and optical parameters. Polycrystalline nature with preferred (1 1 1), (2 0 0) and (2 2 0) orientations was released, the corresponding two theta is 23.15°, 27.42° and 40.26° respectively. Structural parameters as dislocation density, inter-planer distance, the number of crystallites per unit surface area, lattice constant, crystallite size and strain could be determined as a function of annealing. The results confirm the films nanostructure property. The optical gap, refractive index, dielectric constant and optical conductivity increase as a function of annealing. These effects were attributed to the nano structural property and the partial reduction of the defect density.
83 citations
TL;DR: The simulation results and security analysis show that the proposed algorithm not only has a better encryption effect but also has aBetter ability of resisting statistical and differential attacks on comparison with the original proposal.
Abstract: Image encryption is a useful solution to achieve confidentiality while transmitting digital images over unsecure public networks. Among recently proposed encryption schemes, a DNA-based approach Wei et al. (J. Syst. Softw. 85 (2012) 299) with good encryption effect has been reported. An effort has been made in this paper to improve its performance, by infusing more pseudo randomness into this algorithm. For this, three modifications have been suggested: (1) For each pixel of the color image, adoption of multiple DNA encoding rules as against a single rule in Wei et al. (J. Syst. Softw. 85 (2012) 299); (2) multiple DNA operations instead of a single DNA operation as in [17] for diffusion of pixels and (3) combination of the image to be encrypted with another synthetic image as against combination with itself as in [17]. Here, the choice of DNA encoding rule, DNA operation and DNA synthetic image creation are all done based on the outcome of various chaotic maps and systems. The simulation results and security analysis show that our algorithm not only has a better encryption effect but also has a better ability of resisting statistical and differential attacks on comparison with the original proposal.
78 citations
TL;DR: A survey of existing algorithms for no-reference image quality assessment is presented, which includes type of noise and distortions covered, techniques and parameters used by these algorithms, databases on which the algorithms are validated and benchmarking of their performance with each other and also with human visual system.
Abstract: Evaluation of noise content or distortions present in an image is same as assessing the quality of an image Measurement of such quality index is challenging in the absence of reference image In this paper, a survey of existing algorithms for no-reference image quality assessment is presented This survey includes type of noise and distortions covered, techniques and parameters used by these algorithms, databases on which the algorithms are validated and benchmarking of their performance with each other and also with human visual system
77 citations
TL;DR: In this article, photo and thermoluminescence properties of Zn 2 SiO 4 :Re 3+ (Eu, Dy, Sm) phosphors prepared by low temperature solution combustion technique were reported.
Abstract: We report photo and thermoluminescence properties of Zn 2 SiO 4 :Re 3+ (Eu, Dy, Sm) phosphors prepared by low temperature solution combustion technique. The hexagonal phase was confirmed by PXRD patterns. SEM micrographs revealed that morphological features were highly dependent on type of the dopant ion. Characteristic excitation and emission peaks of Eu 3+ , Dy 3+ and Sm 3+ were observed from PL studies. The concentration quenching occurred for 3 mol% Re 3+ doped lanthanide ions, whose critical energy transfer distance ( R c ) was found to be ∼13 Ǻ. The corresponding concentration quenching was verified to be dipole–dipole interaction. The chromaticity co-ordinates of Zn 2 SiO 4 :Eu 3+ /Dy 3+ /Sm 3+ phosphors were located in white region suggests them to be a potential candidate for the production of white light emitting phosphors. Three TL glow peaks in Eu 3+ , Dy 3+ doped and two glow peaks in Sm 3+ doped Zn 2 SiO 4 nanophosphor observed in TL studies indicated that more than one type of traps were created in these phosphors. TL intensity increases linearly in Sm 3+ doped Zn 2 SiO 4 up to 4 kGy and thereafter, it decreases. Up to 4 kGy, the phosphor was quite useful in radiation dosimetry.
77 citations
TL;DR: In this article, a reversible all-optical 4 × 2 encoder using a two-dimensional square lattice rods in air photonic crystal with nonlinear refractive index was designed.
Abstract: In this paper, we designed a reversible all-optical 4 × 2 encoder using a two-dimensional square lattice rods in air photonic crystal with nonlinear refractive index. Our main structure composed of seven vertical waveguide and two elliptical rings. Plane Wave Expansion (PWE) and Finite Difference Time Domain (FDTD) methods are used to calculate band structure and wave propagation in the structure, respectively. Reversible encoder is designed within small size and has ability to be integrated in optical integrated circuits. This reversible encoder is the first optical encoder based on photonic crystals. The results show that our structure could act as an optical reversible encoder.
70 citations
TL;DR: Experimental results demonstrate the effectiveness of the proposed EGF on defect detection in textured surface by using an optimized elliptical Gabor filter.
Abstract: In this paper, a new approach is presented that addresses defect detection in textured surface by using an optimized elliptical Gabor filter (EGF). This newly proposed EGF can be tuned by a genetic algorithm (GA) to have either a form of traditional Gabor filter or a form of shifted ring Gabor filter, with the aim to match with the texture features of a defect-free template acquired in prior during the training process. In the inspection process, each sample under inspection is convoluted with the selected EGF, followed by a gray level thresholding process to generate a binary segmented result. Since only a single filter is utilized during the inspection process, the computational time required for each defective sample is quite limited when compared with those filter bank based schemes. The performance of the proposed method has been extensively evaluated by a variety of samples with different defect type, shape, size and texture background. Experimental results demonstrate the effectiveness of the proposed method on defect detection in textured surfaces.
70 citations
TL;DR: This paper empirically adopt fast and robust face detection algorithm to describe and normalizing facial expression images, and adopts AdaBoost to learn the most discriminative fatigue facial LBP features from a large LBP feature pool, which is a critical problem but seldom addressed in the existing work.
Abstract: Driver fatigue is a major cause of traffic accidents Automatic vision-based driver fatigue recognition is one of the most prospective commercial applications based on facial expression analysis technology Deriving an effective face location from original driver face images is a vital step for successful fatigue facial expression recognition In this paper, we empirically adopt fast and robust face detection algorithm to describe and normalizing facial expression images We evaluate facial representation based on statistical local features, Local Binary Patterns, for person-independent fatigue facial expression recognition, and observe that LBP features perform stably and robustly over a useful range of fatigue face images Moreover, we adopt AdaBoost to learn the most discriminative fatigue facial LBP features from a large LBP feature pool, which is a critical problem but seldom addressed in the existing work We observe in our experiments that Boost-LBP features perform stably and robustly, and best recognition performance is obtained by using SVM with Boost-LBP features
68 citations
TL;DR: In this paper, a numerical simulation and analysis of a copper-indium-gallium-diselenide (CIGS) solar cell performance was performed using the SCAPS software for multiple measurements and the impacts of absorber layer band gap and thickness variation on the cell's output parameters were extensively simulated.
Abstract: This paper shows a numerical simulation and analysis of a copper–indium–gallium–diselenide (CIGS) solar cell performance. The Solar Cell Capacitance Simulator (SCAPS) software is used for multiple measurements. The impacts of absorber layer band gap and thickness variation on the cell's output parameters were extensively simulated. In this study, the CIGS band gap and electron affinity are first defined and formulated as mathematical functions of gallium (Ga) content (“ x ”). Then these new functions can predict the absorber layer band gap at different “ x ” and used to simulate and study of the cell performance. The analysis made from this numerical simulation has revealed the optimum energy band gap of the absorber layer to be 1.2 eV corresponding to x = 0.3. Subsequently, the cell efficiency is innovatively formulated as a function of Ga content in the absorber layer. The effect of absorber layer thickness on cell performance has also been simulated and its range was found to be between 2 μm and 3 μm and it is for the cell with low and optimum absorber layer band gap. Nevertheless, the cell with wide absorber layer band gap will increase the absorber layer thickness thus will cause reduction in cell efficiency.
TL;DR: In this article, the dispersive dark optical solitons with dual-power law nonlinearity, governed by (2+1)-dimensions nonlinear Schrodinger equation are proposed.
Abstract: The article proposes the dispersive dark optical solitons with dual-power law nonlinearity, that are governed by (2+1)-dimensions nonlinear Schrodinger equation. The G ′/ G -expansion method is being utilized to celebrate soliton solution, to this equation, that reveals dark 1-soliton.
TL;DR: A hand gesture recognition method using the Microsoft Kinect has been proposed, which operates robustly in uncontrolled environments and is insensitive to hand variations and distortions, and the use of two different learning techniques, dynamic time warping and hidden Markov model is demonstrated.
Abstract: Human computer interaction through hand gestures is one of the most intuitive ways of communicating with machines and thus it is no surprise that the field of real time gesture detection has seen significant interest among the scientific community in recent times In this paper a hand gesture recognition method using the Microsoft Kinect has been proposed, which operates robustly in uncontrolled environments and is insensitive to hand variations and distortions This demonstrates the use of two different learning techniques, dynamic time warping and hidden Markov model and compare them for real-time implementations The recognition success rate was over 90% The relative advantages of both techniques have been discussed with constraints
TL;DR: The proposed algorithm is proved to produce better enhanced images than the contemporary techniques in terms of contrast per pixel and structural similarity index.
Abstract: Adapted enhancement controlled contrast using adjusted histogram is developed to minimize the problems of over enhancement, saturation artifacts and change in mean brightness with conventional histogram equalization. The input image's histogram is first divided into four sub-histograms based on its median. A clipping process based on the input image mean is applied. Then each partitioned histogram is equalized independently. A contrast enhancement rate is devised in order to achieve the varying contrast for output images. The proposed algorithm is proved to produce better enhanced images than the contemporary techniques in terms of contrast per pixel and structural similarity index.
TL;DR: The proposed algorithm establishes the spatial topology relationship for each point using octree first, then identifies and retains edge points using a simple but effective method, and performs much better compared with other methods.
Abstract: This paper presents a point cloud simplification algorithm with preserved edge based on normal vector. Because edge points have more distinct features than non-edge points, these special points should always be preserved in the point cloud simplification process. The proposed algorithm establishes the spatial topology relationship for each point using octree first, then identifies and retains edge points using a simple but effective method. For non-edge points, delete the least important points until user-specified data reduction ratio is reached. The importance of a non-edge point is measured using the average of the Euclidean distances (based on normal vector) from the point to estimated tangent plane at its each neighborhood point. The experimental results on three test point cloud data sets and two practical data sets of our own demonstrate that the proposed algorithm performs much better compared with other methods.
TL;DR: In this article, an H-shaped resonant ring was used for designing an optical filter, which is designed for coupling of an identical wavelength from upper waveguide to lower one.
Abstract: Photonic crystal based ring resonators are promising structures used for designing optical filters suitable for optical communication networks. In this work we use an H-shaped resonant ring for designing an optical filter. The proposed filter consists of two upper and lower waveguides coupled through an H-shaped resonator which is designed for coupling of an identical wavelength from upper waveguide to the lower one. We use numerical methods such as plane wave expansion and finite difference time domain for performing our simulations and studying the optical properties of the proposed structure. The transmission efficiency and quality factor of our filter is about 100% and 221 relatively.
TL;DR: An improved medical image compression technique based on region of interest (ROI) is proposed to maximize compression and a set of experiments is designed to assess the effectiveness of the proposed compression method.
Abstract: Hospitals and medical centers produce an enormous amount of digital medical images every day, which are used for different purposes such as surgical and diagnostic plans. The ease of storing and transmission of digital medical images is a boon to patients and medical professionals. Due to the large volume of images, image compression is required to reduce the redundancies in image and represents it in shorter manner for efficient archiving and transmission of images. However, compressing digital medical images as the region of interest for diagnosis is generally small when compared to the whole image. Lossless compression techniques compress without loss of any information but have low compression rate, and lossy compression techniques can compress at high compression ratio but with a slight loss of data. Using lossless techniques in medical image does not give enough advantage in transmission and storage and lossy techniques may lose crucial data required for diagnosis. In this paper, an improved medical image compression technique based on region of interest (ROI) is proposed to maximize compression. The image is firstly divided into two parts: ROI regions and non-ROI regions. Lossless compression algorithm is then applied to the marked area of ROI, and image restoration technique and the wavelet-based lossy compression algorithm are utilized to the other area of the image. Finally, a set of experiments is designed to assess the effectiveness of the proposed compression method.
TL;DR: The Single Value Decomposition (SVD) based least squares estimation method is employed for the calibration of Inertial Measurement Unit and Doppler sensors and the experimental results show that this method is able to estimate the alignment parameters reliably.
Abstract: Alignment calibration of Inertial Measurement Unit (IMU) and Doppler sensors is an essential task for precision Inertial Navigation System/Doppler Velocity Log (INS/DVL) integrated navigation. In this paper, the so called alignment calibration problem is transformed into the problem of estimation of the alignment parameters between two point series. The two continuous and synchronized series are designed by the integrated navigation results of INS/GPS and DVL measurements. The Single Value Decomposition (SVD) based least squares estimation method is employed for the calibration. The performance of these estimates is evaluated with experimental data on several cruises in Yangzi River. The experimental results show that this method is able to estimate the alignment parameters reliably. Besides, the alignment parameters can be employed for precision INS/DVL integrated navigation.
TL;DR: This paper introduces two novel methods as image descriptors built upon scale invariant feature transform (SIFT) algorithm and these methods are compared with two popular methods namely, color auto-correlogram and wavelet transform.
Abstract: The large amounts of image collections available from a variety of sources have posed increasing technical challenges to computer systems to store/transmit and index/manage the image data to make such collections easily accessible. To search and retrieve the expected images from the database a content-based image retrieval (CBIR) system is highly demanded. CBIR extracts features of a query image and try to match them with extracted features from images in the database. This paper introduces two novel methods as image descriptors. The basis of the proposed methods is built upon scale invariant feature transform (SIFT) algorithm. After extracting image features using SIFT, k-means clustering is applied on feature matrix extracted by SIFT, and then two new kinds of dimensionality reductions are applied to make SIFT features more efficient and realistic for image retrieval problem. Using the proposed strategies we cannot only take the advantage of SIFT features but also we can highly decrease the memory storage used by SIFT features. As well as in order to compare images we do not need to run the time-consuming matching algorithm of SIFT. Finally, proposed methods are compared with two popular methods namely, color auto-correlogram and wavelet transform. As a result, our proposed retrieval system is fast and accurate and it can efficiently manage large databases. Experimental results on two popular databases, Caltech 101 (with 9144 images) and Li database (with 2360) images, show the superiority and efficiency of the proposed methods.
TL;DR: The study proposes a hybrid wood surface texture features based on defect detection method, which combines the integration of Tamura texture and GLCM method advantages of these two methods, so that the accuracy and robustness of the algorithm are effectively protected.
Abstract: Wood surface defect detection technology is the intersect multidisciplinary technology between computer vision and pattern recognition, which has a high value and is widely used in the field of timber production and deep processing. This paper mainly takes three common defects such as dead knots, poles and living knots of wood for the study, it deeply researches on image segmentation and pattern recognition methods of wood. To ensure the reliability of the results of wood defect recognition, the selection of characteristic values is the crucial aspects of pattern recognition. Haipeng Yu extracted texture of the wood based on GLCM, Xuebing Bai also classified texture of the wood based on GLCM. In addition, researchers used wavelets, Markov random, fractal, local binary pattern and histogram to make some useful attempts with the study of wood texture feature extraction. The above study only applied a texture analysis method. As the diversity and complexity of the wood surface defect images, the success rate of using a certain type of feature detection method is still less than ideal from the application point of view. The study proposes a hybrid wood surface texture features based on defect detection method, which combines the integration of Tamura texture and GLCM method advantages of these two methods, so that the accuracy and robustness of the algorithm are effectively protected.
TL;DR: An easy-to-compute parameter, called Shannon entropy which is from information theory, is employed for quality assessment of speckle patterns and shows that the measurement accuracy of DIC is related on the Shannon entropy ofSpeckle pattern.
Abstract: Digital image correlation (DIC) is a digital-image-based whole-field deformation measuring technique. For use of the technique, the test surface of object has to be covered with random speckle pattern to ensure reliable and accurate matching. In practice, the quality of the speckle pattern has an important influence on the measurement accuracy of DIC. In this paper, an easy-to-compute parameter, called Shannon entropy which is from information theory, is employed for quality assessment of speckle patterns. Two sets of numerical translated tests are performed on three types of speckle patterns and five artificial speckle patterns with different Shannon entropies, respectively. Then, another test is performed on the computer-generated speckle patterns with nonuniform displacement field. All the results show that the measurement accuracy of DIC is related on the Shannon entropy of speckle pattern. Therefore, the speckle pattern with large Shannon entropy should be a so-called good quality speckle pattern.
TL;DR: In this article, thin Nb2O5 films were grown on glass substrates using rf magnetron sputtering technique, in a pure argon atmosphere at different rf power and various substrate temperatures.
Abstract: In the present work, thin Nb2O5 films were grown on glass substrates using rf magnetron sputtering technique, in a pure argon atmosphere at different rf power and various substrate temperatures. X-ray diffraction result revealed the amorphous nature of deposited films. The maximum optical transmittance of about 92% with clear interference pattern was realized from the optical study. A systematic reduction in energy band gap values with increasing substrate temperature and rf power could be attributed to the localized state near the band edges. This hypothesis is consistent with our photoluminescence study where we observe the slight shift in emission peak towards higher wavelength region due to the effect of optical band gap narrowing. The X-ray photoelectron spectroscopic study confirms the film purity and the presence of five-valent niobium (Nb5+) in Nb2O5 films. Surface morphological studies revealed the formation of Nb2O5 films with smooth, uniform and pinhole free in nature. Raman spectra show the Nb O stretching mode of the deposited films.
TL;DR: The substitution of Cu concentrations into the CdS lattice is confirmed by the change in lattice parameters, FTIR and photoluminescence studies as mentioned in this paper, which is useful to design a suitable window material in fabrication for solar cells.
Abstract: Undoped and Cu doped CdS thin films (Cd 1− x Cu x S, x = 0, 0.02, 0.04, 0.06 and 0.08) have been deposited on glass substrate by chemical bath deposition (CBD) method at 80 °C from aqueous solution. Crystalline phases and optical absorption of the films have been well characterized by X-ray diffraction and UV–visible spectrophotometer. Elemental composition of the Cd 1− x Cu x S films was studied by the energy dispersive X-ray (EDX) analysis. The optical absorption and transmission studies revealed that Cd 1− x Cu x S films had direct allowed transition with band gap energy increased from 2.18 to 2.34 eV. The average crystalline size was calculated from X-ray line broadening and it is decreased from 3.09 nm (CdS) to 2.81 nm (Cd 0.96 Cu 0.04 S) then started to increase which was confirmed by SEM studies. The substitution of Cu concentrations into the Cd S lattice is confirmed by the change in lattice parameters, FTIR and photoluminescence studies. The observed lower crystal size (2.81 nm) and higher energy gap (2.28 eV) of Cd 0.96 Cu 0.04 S thin film is useful to design a suitable window material in fabrication for solar cells. The observed shift in both blue band and green band of photoluminescence spectra confirmed the substitution of Cu into Cd S lattice.
TL;DR: In this paper, a self-collimation-based waveguide is proposed to guide the 1.55μm wavelength, most commonly used in telecommunication applications, and the simulations are done using Plane Wave Expansion (PWE) and Finite Difference Time Domain (FDTD) methods.
Abstract: In this paper, one of the most recently introduced phenomena in Photonic Crystal structures was investigated to design self-collimation based waveguides. The advantages of using self-collimation property to design waveguides are discussed and the idea is thoroughly compared with conventional band gap engineered waveguides made by defects. The 2D square lattice waveguides presented in this article, guide the 1.55 μm wavelength, most commonly used in telecommunication applications. Results indicate the high coupling efficiency enhancement in Self-Collimation based waveguides due to using low index contrast materials. The simulations are done using Plane Wave Expansion (PWE) and Finite Difference Time Domain (FDTD) methods and results confirm the value of using self-collimation phenomena in waveguide design.
TL;DR: In this article, the synthesis and characterization of Gd3+ doped Y2O3 phosphors were reported and the effect of variable concentration of europium on photoluminescence (PL) and thermoluminecence (TL) behavior were also studied.
Abstract: The present paper reports the synthesis and characterization photoluminescence and thermoluminescence studies of Gd3+ doped Y2O3 phosphors. The effect of variable concentration of europium on photoluminescence (PL) and thermoluminescence (TL) behavior are also studied. The samples were prepared by solid state synthesis technique which is suitable for large scale production of phosphors. The starting materials used for sample preparation are ZrO2 and Gd2O3 and CaF2 used as a flux. The prepared sample was characterized by X-ray diffraction technique (XRD). The surface morphology of prepared phosphor was determined by field emission gun scanning electron microscopy (FEGSEM) technique. The diffraction pattern was measured by transmission electron microscopy (TEM) with selected area diffraction pattern. All prepared phosphor with variable concentration of Gd3+ (0.2–2 mol%) was studied by photoluminescence analysis it is found that the excitation spectra of prepared phosphor shows broad excitation centered at 249 and 254 nm with few shoulder weak peaks at 275, 308 and 315 nm. The excitation spectra with variable concentration of Gd3+ show strong peaks at 613 nm for 254 nm excitation. For 275 nm excitation strong peaks found at 468, 567, 578 and 608 nm. For recording TL glow curve every time 2 mg phosphor was irradiated by UV 254 nm source and fixed the heating rate at 6.7 °C s−1. Sample shows well resolved peak at 97 °C for 2 mol% of Gd3+. Trapping parameters are calculated for every recorded glow curve.
TL;DR: In this article, the authors studied the photoluminescence properties of fluorine doped tin oxide (SnO 2 : F) thin films with controlled disorder and intrinsic defects induced during elaboration by changing the spray solution flow rate.
Abstract: This paper deals with the study of photoluminescence (PL) and the other physical properties (structural and optoelectronic) of fluorine doped tin oxide (SnO 2 : F) thin films with controlled disorder and intrinsic defects induced during elaboration by changing the spray solution flow rate from 10 to 25 mL min −1 by a step of 5 mL min −1 1. X-Ray Diffraction analysis reveals that SnO 2 :F thin films have a tetragonal structure with (2 0 0 0) preferred orientation. The decrease in the PL intensity peaks with increase in the spray solution flow rate is linked with the decrease in intrinsic defects. The infrared transmission cut-off wavelength of the films shifts towards the lower wavelength with increasing the spray solution flow rate. This result corresponds to an increase of the electron concentration. In fact, the infrared reflectance of the layers shows an increase with increasing electron concentration. All the samples have low transmittance and high reflectance in the near-infrared region. But in the visible, the average transmittance of these films is higher than 85%. The minimum resistivity (1.76 × 10 −4 Ω cm) and maximum Hall mobility ( μ = 47 cm 2 V −1 s −1 ) were obtained at spray solution flow rate equals to 25 mL min −1 . This good optoelectronic quality of this material allows us to use it as an ohmic contact in photovoltaic devices such as CuIn 1− y Ga y S 2 /β-In 2− z Al z S 3 /ZnO. This solar cell has a photovoltaic effect. Thus, the open circuit voltage ( V oc ) and short circuit current density ( J sc ) are equal to 340 mV and 1.25 mA cm −2 , respectively.
TL;DR: In this paper, CdS thin films of 150nm thick were grown by sputtering technique on top of commercially available FTO coated glass substrates. The films were oxidized by subsequently annealed in oxygen ambient at 350°C XRD, EDX, FTIR analysis, UV-vis spectrometry and Hall Effect measurement were used to characterize the films XRD studies confirm the polycrystalline nature of the deposited films with phase transition from hexagonal Cd S to orthorhombic CdO mixed structure.
Abstract: CdS thin films of 150 nm thick were grown by sputtering technique on top of commercially available FTO coated glass substrates The films are oxidized by subsequently annealed in oxygen ambient at 350 °C XRD, EDX, FTIR analysis, UV–vis spectrometry and Hall Effect measurement were used to characterize the films XRD studies confirm the polycrystalline nature of the deposited films with phase transition from hexagonal CdS to orthorhombic CdS:CdO mixed structure It has been observed from the UV–vis and EDX characterizations that the band gap increases with the increase of oxygen concentration incorporated to the annealed CdS thin films as well as with the increase of the oxidation time Band gaps of the films were found to be in the range of 252 – 289 eV Cd S and Cd O stretching vibration was observed from the FTIR spectra The film resistivity and mobility are observed to change inversely with the inclusion of O2 in the CdS thin films
TL;DR: In this paper, the peak shift and broadening of two-phonon Raman scattering relates to phonon confinement and disorder, and a broad Raman peak between 900 and 1100 cm −1 corresponds to superposition of three transverse optical phonons ∼2TO ( X ), 2TO ( W ) and 2TO( L ).
Abstract: Raman scattering from highly/low resistive nanostructured silicon films prepared by metal-assisted chemical etching was investigated. Raman spectrum of obtained silicon nanostructures was measured. Interpretation of observed one and two-phonon Raman peaks are presented. First-order Raman peak has a redshift and broadening. This phenomenon is analyzed in the framework of the phonon confinement model taking into account mechanical stress effects. Second-order Raman peaks were found to be shifted and broadened in comparison to those in the bulk silicon. The peak shift and broadening of two-phonon Raman scattering relates to phonon confinement and disorder. A broad Raman peak between 900 and 1100 cm −1 corresponds to superposition of three transverse optical phonons ∼2TO ( X ), 2TO ( W ) and 2TO ( L ). Influence of excitation wavelength on intensity redistribution of two-phonon Raman scattering components (2TO) is demonstrated and preliminary theoretical explanation of this observation is presented.
TL;DR: An optimum green plane masking (OGPM) using enhanced genetic algorithm (EGA) for the contrast enhancement of retinal images is proposed and shows better enhancement than other reported literature.
Abstract: Masking based techniques are well known and effective for contrast enhancement applications. The conventional unsharp masking in which fixed scale value is using irrespective of the types of test images. In this paper we propose an optimum green plane masking (OGPM) using enhanced genetic algorithm (EGA) for the contrast enhancement of retinal images. The green plane has more details of retinal images than the other two planes. The EGA can adaptively perform the selection, crossover and mutation of chromosomes. First, the proposed approach is evaluated using the standard test images and real time images for different contrast enhancement techniques and optimization techniques. Finally the proposed approach is used for the enhancement of retinal images. Results are analyzed using various performance measures and our OGPM shows better enhancement than other reported literature.
TL;DR: This paper successfully broke the scheme with the chosen plaintext attack method and showed that all kinds of DNA encoding and decoding schemes used in this encryption scheme are equivalent to each other, which makes it a confusion-only encryption scheme.
Abstract: We studied the security features of a recently proposed image encryption scheme [Zhang et al., Optik 124(18) (2013) 3596] based on DNA sequence operation and hyper-chaotic system. We showed that all kinds of DNA encoding and decoding schemes used in this encryption scheme are equivalent to each other, which makes it a confusion-only encryption scheme. This paper successfully broke the scheme with the chosen plaintext attack method.