Video frame deletion detection based on time–frequency analysis

With the emergence of diverse multimedia editing software, a great number of edited or tampered video resources appear on the Internet, some of which can mix with the genuine ones. Digital video authenticity is an important step to make the best use of these video resources. As a common video forgery operation, frame tampering can change the video content and confuse viewers by removing or inserting some specific frames. In this paper, we explore the traces created by compression process and propose a new method to detect frame tampering based on the high-frequency features of reconstructed DCT coefficients in the tampered sequences. Experimental results demonstrate that our proposed method can effectively detect frame tampering operation, and accurately locate the breakpoint of frame tampering in the streams.     

A restoration–segmentation algorithm based on flexible Arnoldi–Tikhonov method and Curvelet denoising

In this paper, we illustrate a two-stage algorithm consisting of restoration and segmentation to reach binary segmentation from the noisy and blurry image. The results of our method can be applied in main fields of the image processing such as object extraction. In the first stage, we have a linear discrete ill-posed problem with a noise-contaminated right-hand side, arising from the image restoration. We consider problems in which the coefficient matrix is the sum of Kronecker products of matrices and present a global flexible Arnoldi–Tikhonov method coupled with the generalized cross-validation for the computation of the regularization parameter at each iteration. The proposed algorithm is based on the global Arnoldi method that allows using a more flexible solution subspace. In the second stage, we segment the restored image in order to reach a binary image in which the target object is emphasized. In our segmentation method, we use Gaussian scale-space technique to compute discrete gradients of the restored image for pre-segmenting. Also, in order to denoise, we use a tight frame of Curvelet transforms and thresholding which is based on the principle obtained by minimizing Stein’s unbiased risk estimate. This algorithm has an iterative part based on the iterative part of TFA (Cai et al. in SIAM J Imaging 6(1):464–486, 2013), but we use eigenvectors of Hessian matrix of image for improving this part. Theoretical properties of the method of both stages and numerical experiments are presented.     

Effective Hamiltonians for heterostructures based on direct-gap III–V semiconductors. The kp perturbation theory and the method of invariants

A sequential procedure for obtaining effective kp Hamiltonians for arbitrary heterostructures based on direct-gap semiconductors with identical lattice parameters is suggested. The heterostructure potential is described with the help of characteristic functions f _l (a), which indicate atom substitution in sublattice l of the reference crystal in unit cell a. The kp perturbation theory for heterostructures, which takes into account the scattering effects of charge carriers on the additional local potential that emerges due to atom substitution, is developed. A method of constructing the corresponding effective kp Hamiltonians by the method of invariants, which takes into account the microscopic symmetry of interfaces, is suggested. Along with the band parameters, the obtained Hamiltonians contain additional parameters, which have no analogs in bulk materials. The derivation of the effective Hamiltonians of bands Γ₁, Γ₆, Γ₁₅, and Γ₈ in heterostructures based on cubic III–V semiconductors with atom substitution in one sublattice is given as an example.     

Joint spatial-frequency blind multiuser detection based on LCCMA

Multicarrier code division multiple access (MC-CDMA) has the ability to combat with frequency selective fading and antenna array can enhance the performance of system. The paper proposes a novel joint spatial-frequency blind multiuser detection for antenna array MC-CDMA based on linear constraint constant modulation algorithm (LCCMA), which has robust performance and can ensue the weight vectors to converge to that of the desired user. Simulation indicates the proposed algorithm has better bit error ratio (BER) performance than that of the traditional beamforming-based two-step algorithm.     

Side chain effect on photovoltaic properties of D–A copolymers based on benzodithiophene and thiophene-substituted bithiazole

Two donor–acceptor (D−A) copolymers, PEHBDT-BTz and PODBDT-BTz, containing the same backbone of benzodithiophene (BDT) and bithiazole (BTz) units but different side chains were designed and synthesized. Effects of the side chains of BDT and BTz units on solubility, absorption spectra, energy levels, film morphology, and photovoltaic properties of the polymers were investigated. Results showed that the more branched side chains could increase the molecular weight and the introduction of alkylthienyl groups into BTz unit benefits to broaden the absorption and lower the bandgaps as well as deepen HOMO levels, which are propitious to improve the short-circuit current density (J_sc) and open-circuit voltage (V_oc) of photovoltaic cells. Polymer solar cells (PSCs) were prepared with the polymers as electron donors and PCBM as an acceptor. The device fabrication conditions, including the additive, the different acceptor and blend ratio of the polymer donor and acceptor, have been optimized. PCE of PSCs based on the copolymers varied from 2.92% for PODBDT-BTz to 3.71% for PEHBDT-BTz, depending on the type and topology of the side chains on the BDT moiety. The results indicate that an appropriate choice of side chains on the backbone is an effective way to improve photovoltaic performance of the related PSCs.     

Range-free wireless sensor networks localization based on?hop-count quantization

Localization is one of the most important research issues in Wireless Sensor Networks (WSNs). Recently, hop-count-based localization has been proposed as a cost-effective alternative to many expensive hardware-based localization algorithms. The basic idea of many hop-count-based localization algorithms is to seek a transformation from hop-count information to distance (e.g. DV-hop algorithm of Niculescu and Nath in Global Telecommunications Conference, vol.?5, pp.?2926?C2931, 2001) or location (e.g. MDS algorithm of Shang et al. in International Symposium on Mobile Ad Hoc Networking and Computing, pp.?201?C212, 2003) information. Traditionally, hop-counts between any pair of nodes can only take on integer value regardless of relative positions of nodes in the hop. We argue that by partitioning a node??s one-hop neighbor set into three disjoint subsets according to their hop-count values, the integer hop-count can be transformed into a real number accordingly. The transformed real number hop-count is then a more accurate representation of a node??s relative position than an integer-valued hop-count. In this paper, we present a novel algorithm termed HCQ (hop-count quantization) to perform such transformation. We then use the transformed real number hop-count to solve WSNs localization problems based on the MDS (multidimensional scaling) method. Simulation results show that the performance of the MDS algorithm using the real number hop-count outperforms those which use integer hop-count values.     

An optimized content delivery approach based on demand–supply theory in disruption-tolerant networks

Telecommunication Systems - Disruption-tolerance networks (DTNs) are suitable for applications that may lack continuous network connectivity. Examples of such applications include coupon...     

Retrieval of head–neck medical images using Gabor filter based on power-law transformation method and rank BHMT

This research aims to work on the specific medical domain. In this work, retrieval of the head–neck medical images from a database is discussed. Content-based medical image retrieval system (CBMIR) is used for retrieving the head–neck images. CBMIR is automatic and more efficient compared with the text-based approach. Shape and texture features are used for constructing feature vector. Texture feature is extracted using a modified Gabor filter based on power-law transformation method. Shape feature is extracted using rank BHMT (rank-order blur hit or miss transformation) method. Shape and texture features are combined to form a single feature vector. Threshold value very near to zero is used to retrieve images from the database. The proposed method is compared with log-Gabor filters and rank BHMT method. Combinations of modified Gabor filter with rank BHMT gave better performance than other methods.     

Human–robot interaction based on gesture and movement recognition

Human–robot interaction (HRI) has become a research hotspot in computer vision and robotics due to its wide application in human–computer interaction (HCI) domain. Based on the explored algorithms of gesture recognition and limb movement recognition in somatosensory interaction, an HRI model of a robotic arm is proposed for robot arm manipulation. More specifically, 3D SSD architecture is used for the location and identification of gesture and arm movement. Then, DTW template matching algorithm is adopted to trace the dynamic gestures. The interactive scenarios and interactive modes are designed for experiment and implementation. Virtual interactive experimental results have demonstrated the usefulness of our method.     

Preparation and properties of CaTiO3 ∶ Zn nanoparticles based on sol-gel method

采用溶胶凝胶法制备了CaTiO3∶Zn纳米粉体,研究了所制粉体的微观结构及性能.结果表明,所制粉体粒径约50 nm,主晶相为CaTiO3,Zn以Zn2TiO4形式存在于晶相中.1 150℃下烧结所得CaTiO3∶Zn纳米粉体性能较优:比固相法的烧结温度降低约250℃,相对介电常数εr=155,品质因数Q·f提高至6 633 GHz.     

Wavelength-shift detection system based on matching-FBG with enhanced temperature sensitivity

FBGsensorshaveattractedaconsiderableamountof interestinthelasttenyearsforuseinoptical fibersens ingapplications[13].Variouswavelength shiftdetectionschemesbasedonFBGsensorshavebeendeveloped,in cludingtheopticalfiltering,interferometry,etc.Someof thesesche…     

Image segmentation based on the Poincaré map method

Active contour models (ACMs) integrated with various kinds of external force fields to pull the contours to the exact boundaries have shown their powerful abilities in object segmentation. However, local minimum problems still exist within these models, particularly the vector field's "equilibrium issues." Different from traditional ACMs, within this paper, the task of object segmentation is achieved in a novel manner by the Poincaré map method in a defined vector field in view of dynamical systems. An interpolated swirling and attracting flow (ISAF) vector field is first generated for the observed image. Then, the states on the limit cycles of the ISAF are located by the convergence of Newton-Raphson sequences on the given Poincaré sections. Meanwhile, the periods of limit cycles are determined. Consequently, the objects' boundaries are represented by integral equations with the corresponding converged states and periods. Experiments and comparisons with some traditional external force field methods are done to exhibit the superiority of the proposed method in cases of complex concave boundary segmentation, multiple-object segmentation, and initialization flexibility. In addition, it is more computationally efficient than traditional ACMs by solving the problem in some lower dimensional subspace without using level-set methods.     

High open-circuit voltage polymer solar cells based on D–A copolymer of indacenodithiophene and fluorine-substituted benzotriazole

A medium band gap D–A copolymer of indacenodithiophene (IDT) and fluorinated dithienylbenzotriazole (FBTA), PIDT-FBTA, was synthesized for the application as donor material in polymer solar cells (PSCs). PIDT-FBTA showed deeper highest occupied molecular orbital (HOMO) energy level due to the strong electron-withdrawing difluorine substitution on benzotriazole acceptor unit in the D–A copolymer. The PSCs based on PIDT-FBTA:PC₇₀BM (1:3) exhibited a high V_oc of 0.90 V and a power conversion efficiency (PCE) of 3.62% under the illumination of AM 1.5G, 100 mW cm⁻². The device performance was further improved by methanol treatment with PCE increased to 4.90% and V_oc increased to 0.92 V.     

SPICE modelling of hot-carrier degradation in Si1–xGex S/D and HfSiON based pMOS transistors

Hot-carrier degradation in pMOS transistors with Si_1–xGe_x implantations in the source and drain areas is analyzed (SiGe S/D). A simulation methodology is developed to translate the effects to circuit simulators. This methodology is applied to study hot-carrier degradation in CMOS inverters designed with SiGe S/D pMOS transistors. The results show that although pMOS transistors with embedded SiGe S/D have a better device performance, these devices are more sensitive to hot-carrier degradation at both the device and circuit levels.     

D–A copolymer with high ambipolar mobilities based on dithienothiophene and diketopyrrolopyrrole for polymer solar cells and organic field-effect transistors

Donor–acceptor (D–A) type conjugated polymers have been developed to absorb longer wavelength light in polymer solar cells (PSCs) and to achieve a high charge carrier mobility in organic field-effect transistors (OFETs). PDTDP, containing dithienothiophene (DTT) as the electron donor and diketopyrrolopyrrole (DPP) as the electron acceptor, was synthesized by stille polycondensation in order to achieve the advantages of D–A type conjugated polymers. The polymer showed optical band gaps of 1.44 and 1.42 eV in solution and in film, respectively, and a HOMO level of 5.09 eV. PDTDP and PC₇₁BM blends with 1,8-diiodooctane (DIO) exhibited improved performance in PSCs with a power conversion efficiency (PCE) of 4.45% under AM 1.5G irradiation. By investigating transmission electron microscopy (TEM), atomic force microscopy (AFM), and the light intensity dependence of J_SC and V_OC, we conclude that DIO acts as a processing additive that helps to form a nanoscale phase separation between donor and acceptor, resulting in an enhancement of μ_h and μ_e, which affects the J_SC, EQE, and PCE of PSCs. The charge carrier mobilities of PDTDP in OFETs were also investigated at various annealing temperatures and the polymer exhibited the highest hole and electron mobilities of 2.53 cm² V⁻¹ s⁻¹ at 250 °C and 0.36 cm² V⁻¹ s⁻¹ at 310 °C, respectively. XRD and AFM results demonstrated that the thermal annealing temperature had a critical effect on the changes in the crystallinity and morphology of the polymer. The low-voltage device was fabricated using high-k dielectric, P(VDF-TrFE) and P(VDF-TrFE-CTFE), and the carrier mobility of PDTDP was reached 0.1 cm² V⁻¹ s⁻¹ at V_d = −5 V. PDTDP complementary inverters were fabricated, and the high ambipolar characteristics of the polymer resulted in an output voltage gain of more than 25.     

A novel node selection scheme for energy-efficient cooperative spectrum sensing using D–S theory

Wireless Networks - Energy-efficient and reliable detection of available spectrum are fundamental objectives for cooperative spectrum sensing (CSS) in cognitive radio sensor networks (CRSNs). In...     

Low observable group targets detection based on space–frequency cascaded adaptive processing for MIMO OTH radar

Multidimensional Systems and Signal Processing - The spread of sea clutter in the Doppler domain caused by multi-mode propagation would make it difficult for over-the-horizon radar to detect low...     

Visible–infrared person re-identification based on key-point feature extraction and optimization

Feature extraction for visible–infrared person re-identification (VI-ReID) is challenging because of the cross-modality discrepancy in the images taken by different spectral cameras. Most of the existing VI-ReID methods often ignore the potential relationship between features. In this paper, we intend to transform low-order person features into high-order graph features, and make full use of the hidden information between person features. Therefore, we propose a multi-hop attention graph convolution network (MAGC) to extract robust person joint feature information using residual attention mechanism while reducing the impact of environmental noise. The transfer of higher order graph features within MAGC enables the network to learn the hidden relationship between features. We also introduce the self-attention semantic perception layer (SSPL) which can adaptively select more discriminant features to further promote the transmission of useful information. The experiments on VI-ReID datasets demonstrate its effectiveness.     

Photoelectric and optical properties of Schottky-barrier photodiodes based on IrSi–Si

The basic properties in the Schottky-barrier photodiodes (SBPDs) can be reduced to photon absorption in the silicide layer and internal photoemission of charge carriers from a metal to a semiconductor. Therefore, the quantum efficiency and photoresponse of these photodiodes (PDs) are primarily determined by electronic and optical processes in the metal silicide rather than in the semiconductor. This implies that, to a first approximation, the SBPD photoresponse is independent of semiconductor parameters such as the doping level, degree of compensation of impurities, and minority-carrier lifetime. The main reasons for photoresponse nonuniformity in multielement detector arrays are thereby ruled out.