Blind image watermarking via exploitation of inter-block prediction and visibility threshold in DCT domain

In this paper, the backward-propagation neural network (BPNN) technique and just-noticeable difference (JND) model are incorporated into a block-wise discrete cosine transform (DCT)-based scheme to achieve effective blind image watermarking. To form a block structure in the DCT domain, we partition a host image into non-overlapped blocks of size 8 × 8 and then apply DCT to each block separately. By referring to certain DCT coefficients over a 3 × 3 grid of blocks, the BPNN can offer adequate predictions of designated coefficients inside the central block. The watermarking turns out to be a process of adjusting the relationship between the intended coefficients and their BPNN predictions subject to the JND. Experimental results show that the proposed scheme is able to withstand a variety of image processing attacks. Compared with two other schemes that also utilize inter-block correlations, the proposed one apparently exhibits superior robustness and imperceptibility under the same payload capacity.     

Realizing high breakdown voltage for a novel interface charges islands structure based on partial-SOI substrate

A novel interface charge islands partial-SOI (ICI PSOI) high voltage device with a silicon window under the source and its mechanism are studied in this paper. ICI PSOI is characterized by a series of equidistant high concentration n⁺-regions on the bottom interface of top silicon layer. On the condition of high-voltage blocking state, inversion holes located in the spacing of two n⁺-regions effectively enhance the electric field of the buried oxide layer (E_I) and reduce the electric field of the silicon layer (E_S), resulting in a high breakdown voltage (V_B). It is shown by the simulations that the enhanced field ΔE_I and reduced field ΔE_S by the accumulated holes reach to 449 V/μm and 24 V/μm, respectively, which makes V_B of ICI PSOI increase to 663 V from 266 V of the conventional PSOI on 5 μm silicon layer and 1 μm buried oxide layer with the same silicon window length. On-resistance of ICI PSOI is lower than that of the conventional PSOI. Moreover, self-heating-effect is alleviated by the silicon window in comparison with the conventional SOI at the same power of 1 mW/μm.     

Highly enhanced light extraction from organic light emitting diodes with little image blurring and good color stability

We report a highly enhanced light extraction from a top emission organic light emitting diode with little image blurring and color variation with viewing angle. Direct integration of a high refractive index micro lens array on the top of the transparent indium zinc oxide top electrode of a green phosphorescent OLED showed a significant enhancement of light extraction to get EQE of 44.7% from 27.6%, the power efficiency of 134.7 lm/w from 85.9 lm/W and the current efficiency of 217.2 cd/A from 120.7 cd/A without image blurring. In addition, the device showed excellent color stability on viewing angle with Commission Internationale de l’Eclairage (CIE) coordinate of Δx = 0.01, Δy = 0.01 as the viewing angle varied from 0° to 60°.     

Analysis of recursive convolutional codes and turbo codes as sources with memory

The paper proposes a general method to analyze discrete sources with memory. Besides the classical entropy, we define new information measures for discrete sources with memory, similar to the information quantities specific to discrete channels. On the base of this method, we show for the first time that, as result of convolutional and turbo encoding, sources with memory are obtained. We apply this information analysis method for the general case of a recursive convolutional encoder of rate R_CC = 1/n₀ and memory of order m, and for a turbo encoder of rate R_TC = 1/3, with two systematic recursive convolutional component encoders. Each component encoder has memory of order m, and is built based on the same primitive feedback polynomial. For the convolutional and turbo codes, the information quantities H(Y/S), H(S,Y), H(S/Y), H(Y), H(S) and I(S,Y) have been computed, where S and Y denote the set of states and the set of messages of the encoder, respectively. The analysis considered two cases: n₀ ≤ m + 1 and n₀ > m + 1. When n₀ = m + 1, the mutual information I(S,Y) is maximum and equal to m, as is the entropy of the set of states. For turbo codes, the quantity I(S,Y) also depends on the input bit and on its probability.     

Improved image tamper localisation using chaotic maps and self-recovery

In this paper an image tamper localisation scheme is proposed in which authentication bits of a 2 × 2 image block are generated using the chaotic maps. Further the scheme is improved by including a self-recovery method to recover the tampered regions. To improve the quality of the recovered image, two different sets of restoration bits of a block are generated and each one is embedded into randomly selected distinct blocks. The proposed tamper detection scheme performs better than some of the recent schemes proposed by the researchers. The experimental results demonstrate the accuracy and fragility of the tamper detection scheme, and the efficacy of the recovery method.     

A dual color images watermarking scheme based on the optimized compensation of singular value decomposition

This paper proposes a novel watermarking algorithm based on the improved compensation of SVD for embedding the color image watermark into the color host image. Firstly, the watermark bit is embedded into 4 × 4 block by modifying the second row first column and the third row first column elements of U component after SVD. Then, the embedded block is compensated by the improved optimization operation for obtaining higher PSNR and larger threshold T. The embedded watermark is extracted from various attacked images by using the relation between the modified elements of U component without resorting to the original data. Moreover, the proposed algorithm overcomes the problem of false positive detection. The experimental results show that the proposed algorithm not only guarantees the invisibility and robustness of the watermark, but also has better performance than other methods mentioned in this paper.     

An augmented Lagrangian approach to general dictionary learning for image denoising

This paper presents an augmented Lagrangian (AL) based method for designing of overcomplete dictionaries for sparse representation with general l_q-data fidelity term (q ? 2). In the proposed method, the dictionary is updated via a simple gradient descent method after each inner minimization step of the AL scheme. Besides, a modified Iterated Shrinkage/Thresholding Algorithm is employed to accelerate the sparse coding stage of the algorithm. We reveal that the dictionary update strategy of the proposed method is different from most of existing methods because the learned dictionaries become more and more complex regularly. An advantage of the iterated refinement methodology is that it makes the method less dependent on the initial dictionary. Experimental results on real image for Gaussian noise removal (q = 2) and impulse noise removal (q = 1) consistently demonstrate that the proposed approach can efficiently remove the noise while maintaining high image quality.     

Power assignment problems in wireless communication: Covering points by disks,reaching few receivers quickly,and energy-efficient travelling salesman tours

In this paper, we present approximation algorithms for a variety of problems occurring in the design of energy-efficient wireless communication networks. We first study the k-station network problem, where for a set S of stations and some constant k, one wants to assign transmission powers to at most k senders such that every station in S can receive a signal from at least one sender. We give a (1 + ?)-approximation algorithm for this problem. The second problem deals with energy-efficient networks, allowing bounded hop multicast operations, that is given a subset C of the stations S and a designated source node s ∈ S, we want to assign powers to the sending stations, such that every node in C can be reached by a transmission from s within k hops. For this problem, we provide an algorithm which runs in time linear in ∣S∣. The last problem deals with a variant of the non-metric TSP problem where the edge costs correspond to the Euclidean distances to the power of some α ? 1; this problem is motivated by data aggregation schemes in wireless sensor networks. We provide a simple constant approximation algorithm, which improves upon previous results when 2 ? α ? 2.7.     

Driving current and temperature dependent magnetic-field modulated electroluminescence in Alq3-based organic light emitting diode

Driving current and temperature dependences of magnetic-field modulated electroluminescence (EL) in tris(8-hydroxyquinoline) aluminum (Alq₃)-based OLEDs have been thoroughly investigated. At low temperatures, the applied magnetic-field induces a sharp increase of the EL in low field regime (B ? 35 mT) and a slow but apparent decrease at high fields (35 ? B ? 500 mT). The low-field increase in EL (LFE) survives at all working temperatures while the high-field decrease (HFE) gradually disappears as temperature is increased. At a given temperature, the higher the current level, the smaller LFE and stronger HFE are observed. To explain the observed MFEs a composite model based on magnetic-field dependent singlet-to-triplet conversion of electron-hole pairs and magnetic-field mediated triplet–triplet annihilation process is proposed in this paper.     

Reversible data hiding of a VQ index table based on referred counts

This paper presents a new reversible VQ-based hiding scheme that can recover the original VQ compressed codes after data extraction. Our scheme sorts a VQ codebook using the referred counts. The VQ codebook is then divided into 2^B clusters and half of these clusters are used to embed secret data, in which B denotes the size of the secret data embedded into each VQ index. Compared to Chang et al.’s scheme, which divides a sorted VQ codebook into 2^B?1 × 3 clusters and uses the front one-third clusters to embed secret data, our method can embed more data. Moreover, indicator, index exchanging, and side-match prediction schemes are proposed to further improve our scheme. Under the same sorted VQ codebook, the experimental results demonstrate that our data hiding algorithm has higher capacities and better compression rates.     

Tetrolet transform: A new adaptive Haar wavelet algorithm for sparse image representation

In order to get an efficient image representation we introduce a new adaptive Haar wavelet transform, called Tetrolet Transform. Tetrolets are Haar-type wavelets whose supports are tetrominoes which are shapes made by connecting four equal-sized squares. The corresponding fast filter bank algorithm is simple but very effective. In every level of the filter bank algorithm we divide the low-pass image into 4 × 4 blocks. Then in each block we determine a local tetrolet basis which is adapted to the image geometry in this block. An analysis of the adaptivity costs leads to modified versions of our method. Numerical results show the strong efficiency of the tetrolet transform for image approximation.     

Two-layered structure for optimally essential secret image sharing scheme

This paper presents a two-layered structure for optimally sharing a secret image among s essential and n − s non-essential shared shadows using the (t, s, k, n) essential thresholds, that t essential shared shadows and totally k shared shadows are needed to recover the secret image. The presented two-layered structure includes one user-defined parameter m to determine different kinds of optimal results. m = 1 leads to minimum size of total shared shadows (ST) and size of an essential shared shadow is close to size of a non-essential shared shadow. On the other hand, m = t leads to size of an essential shared shadow being twice of size of a non-essential shared shadow to signify the importance of an essential shared shadow. Moreover, the proposed structure overcomes the threshold fulfillment problem in Chen’s scheme (Chen, 2016). Theoretical analyses and experimental results show that the proposed scheme exhibits secure with optimal sharing ratios among related works.     

High-resolution wide-band LC-VCO for reliable operation in phase-locked loops

This paper presents a novel sizing scheme to implement the array of switches in the capacitor bank of LC-VCOs for oscillation frequency coarse control. The proposed scheme allows increasing the number of elements in the capacitor bank beyond the values typically achieved by binary scaling, endowing the resulting LC-VCO with a wider tuning range and high frequency resolution, which is beneficial for the implementation of reliable phase-locked loops. Two different gigahertz LC-VCOs have been designed to validate the proposed scheme. The prototypes, fabricated in a cost-effective 0.18 μm CMOS process, cover a 700 MHz frequency range from 1.35 GHz to 2.05 GHz and from 2.05 GHz to 2.75 GHz, respectively, with a phase noise figure of − 122 dBc/Hz and − 119.5 dBc/Hz at 1 MHz from the mid-range carriers, and a power consumption of 18 mW. These figures result in a respective FOM_T of − 186.4 dBc/Hz and − 183.8 dBc/Hz. The performance of the fabricated LC-VCOs is achieved in each case with a dense coarse tuning range of 128 levels, which allows, respectively, a fine tuning gain smaller than 40 MHz V^− 1.     

Compact differential bandpass filter with a narrow notched band using APCL structure suitable for UWB application

A compact differential band pass filter with asymmetric parallel-coupled lines (APCL) and center frequency of 5.6 GHz is proposed in this paper. The APCL suppresses unwanted RFID signals by introducing a fully tunable notched band at 6.8 GHz. By combining the concept of transmission matrix with modal analysis and extracting a novel model for symmetric three parallel coupled lines (SPCL), role of each resonant frequency is clearly explained. Measurement results in the differential mode show a pass band from 3.1 to 8.1 GHz and a wide stop band from 9.1 to 16 GHz with attenuation of more than 20 dB. In addition, S₂₁ in common mode is lower than −10.5 dB over the pass band.     

A UWB CMOS low-noise amplifier with noise reduction and linearity improvement techniques

In this paper, a highly linear CMOS low noise amplifier (LNA) for ultra-wideband applications is presented. The proposed LNA improves both input second- and third-order intercept points (IIP2 and IIP3) by canceling the common-mode part of all intermodulation components from the output current. The proposed LNA structure creates equal common-mode currents with the opposite sign by cascading two differential pairs with a cross-connected output. These currents eliminate each other at the output and improve the linearity. Also, the proposed LNA improves the noise performance by canceling the thermal noise of the input and auxiliary transistors at the output. Detailed analysis is provided to show the effectiveness of the proposed LNA structure. Post-layout circuit level simulation results using a 90 nm RF CMOS process with Spectre-RF reveal 9.5 dB power gain, -3 dB bandwidth (BW_−3dB) of 8 GHz from 2.4 GHz to 10.4 GHz, and mean IIP3 and IIP2 of +13.1 dBm and +42.8 dBm, respectively. The simulated S₁₁ is less than −11 dB in whole frequency range while the LNA consumes 14.8 mW from a single 1.2 V power supply.     

Defect studies in Cu2ZnSnSe4 and Cu2ZnSn(Se0.75S0.25)4 by admittance and photoluminescence spectroscopy

To achieve higher record efficiencies for solar cells containing Cu₂ZnSnSe₄ (CZTSe), Cu₂ZnSnS₄ (CZTS) or their solid solution Cu₂ZnSn(Se_xS_1?x)₄ (CZTSSe) as an absorber, it is necessary to obtain more knowledge about defect structure of these materials. In this work, admittance spectroscopy (AS) and low temperature photoluminescence spectroscopy (PL) were used for defect studies. Admittance spectroscopy in the frequency range from 20 Hz to 10 MHz was used for studies of CZTSe/CdS and CZTSSe/CdS monograin layer heterojunctions. The measurement temperature varied from 140 K to 245 K. Two defect states (labelled E_A1 and E_A2) were found in Cu₂ZnSnSe₄ and Cu₂ZnSn(Se_0.75S_0.25)₄. In different CZTSe/CdS heterojunctions the E_A2 state was present at 74 meV, but the second E_A1 defect state changed from 87 meV to 100 meV during time and had varying properties. In Cu₂ZnSn(Se_0.75S_0.25)₄ the E_A2 state was found at 25 meV. The E_A1 state at 154 meV showed the same properties as the two defect levels in CZTSe. In both cases the E_A2 defect state was attributed to an acceptor defect and the E_A1 state with changing properties to interface states. The detected PL bands were at 0.946 eV in CZTSe and at 1.028 eV in Cu₂ZnSn(Se_0.75S_0.25)₄. Obtained by PL measurements, defect states at 69 meV in CZTSe and at 39 meV in Cu₂ZnSn(Se_0.75S_0.25)₄ were attributed to the same acceptor defect that was found from the AS measurements.     

Low power high gain CMOS LNA based on inverter cell and self-body bias for UWB receivers

A low-power low-noise amplifier (LNA) utilized a resistive inverter configuration feedback amplifier to achieve the broadband input matching purposes. To achieve low power consumption and high gain, the proposed LNA utilizes a current-reused technique and a splitting-load inductive peaking technique of a resistive-feedback inverter for input matching. Two wideband LNAs are implemented by TSMC 0.18 μm CMOS technology. The first LNA operates at 2–6 GHz. The minimum noise figure is 3.6 dB. The amplifier provides a maximum gain (S₂₁) of 18.5 dB while drawing 10.3 mW from a 1.5-V supply. This chip area is 1.028×0.921 mm². The second LNA operates at 3.1–10.6 GHz. By using self-forward body bias, it can reduce supply voltage as well as save bias current. The minimum noise figure is 4.8 dB. The amplifier provides a maximum gain (S₂₁) of 17.8 dB while drawing 9.67 mW from a 1.2-V supply. This chip area is 1.274×0.771 mm².     

SIFT-flow-based color correction for multi-view video

During the multi-view video acquisition, color variation across the views tends to be incurred due to different camera positions, orientations, and local lighting conditions. Such color variation will inevitably deteriorate the performance of the follow-up multi-view video processing, such as multi-view video coding (MVC). To address this problem, an effective color correction algorithm, called the SIFT flow-based color correction (SFCC), is proposed in this paper. First, the SIFT-flow technique is used to establish point-to-point correspondences across all the views of the multi-view video. The average color is then computed based on those identified common corresponding points and used as the reference color. By minimizing the energy of the difference yielded between the color of those identified common corresponding points in each view with respect to the reference color, the color correction matrix for each view can be obtained and used to correct its color. Experimental results have shown that the proposed SFCC algorithm is able to effectively eliminate the color variation inherited in multi-view video. By further exploiting the developed SFCC algorithm as a pre-processing for the MVC, extensive simulation results have shown that the coding efficiency of the color-corrected multi-view video can be greatly improved (on average, 0.85 dB, 1.27 dB and 1.63 dB gain for Y, U, and V components, respectively), compared with that of the original multi-view video without color correction.     

Electrical characterization and TCAD simulations of multi-gate bulk nMOSFET

A multi-gate nMOSFET in bulk CMOS process has been fabricated by integration of polysilicon-filled trenches. We have simulated its electrical characteristics by using TCAD software and compared them with results obtained from electrical measurements. The threshold voltage and the subthreshold slope of the top gate have been extracted and we found a good accordance, for both parameters, between the measurements (V_TH=0.59 V, S=90 mV/dec) and simulations (V_TH=0.50 V, S=92 mV/dec). The surface channel effective mobility of this multi-gate MOSFET was extracted and evaluated with both effective length and surface. The studies revealed that mobility degraded towards smaller dimensions of the MOS channel. At last, the Si/SiO₂ interface quality studies were carried out. We noticed that the injected donor traps have a larger influence on the current–voltage characteristics than acceptor-like traps. With its good electrical performances, this low-cost multi-gate MOSFET technology presents interesting perspective in CMOS image sensors and more generally in analog application taking benefit of the multi-threshold for example.     

The effect of annealing on the physical properties of thermally evaporated CuIn2n+1S3n+2 thin films (n=0, 1, 2 and 3)

In this study, the annealing effect on structural, electrical and optical properties of CuIn_2n+1S_3n+2 thin films (n=0, 1, 2 and 3) are investigated. CuIn_2n+1S_3n+2 films were elaborated by vacuum thermal evaporation and annealed at 150 and 250 °C during 2 h in air atmosphere. XRD data analysis shows that CuInS₂ and CuIn₃S₅ (n=0 and 1) crystallize in the chalcopyrite structure according to a preferential direction (112), CuIn₅S₈ and CuIn₇S₁₁ (n=2 and 3) crystallize in the cubic spinel structure with a preferential direction (311). The optical characterization allowed us to determine the optical constants (refractive indexes 2.2–3.1, optical thicknesses 250–500 nm, coefficients of absorption 10⁵ cm^?1, coefficients of extinction <1, and the values of the optical transitions 1.80–2.22 eV) of the samples of all materials. We exploited the models of Cauchy, Wemple–DiDomenico and Spitzer–Fan for the analysis of the dispersion of the refractive index and the determination of the optical and dielectric constants.