Cooperative Secret Communication with Artificial Noise in Symmetric Interference Channel

We consider the symmetric Gaussian interference channel where two users try to enhance their secrecy rates in a cooperative manner. Artificial noise is introduced along with useful information. We derive the power control and artificial noise parameter for two kinds of optimal points, max-min point and single user point. It is shown that there exists a critical value $P_c$ of the power constraint, below which the max-min point is an optimal point on the secrecy rate region, and above which time-sharing between single user points achieves larger secrecy rate pairs. It is also shown that artificial noise can help to enlarge the secrecy rate region, in particular on the single user point.Comment: 3 pages, 3 figures, to appear in IEEE Communications Letter

Information Splitting for Big Data Analytics

Many statistical models require an estimation of unknown (co)-variance parameter(s) in a model. The estimation usually obtained by maximizing a log-likelihood which involves log determinant terms. In principle, one requires the \emph{observed information}--the negative Hessian matrix or the second derivative of the log-likelihood---to obtain an accurate maximum likelihood estimator according to the Newton method. When one uses the \emph{Fisher information}, the expect value of the observed information, a simpler algorithm than the Newton method is obtained as the Fisher scoring algorithm. With the advance in high-throughput technologies in the biological sciences, recommendation systems and social networks, the sizes of data sets---and the corresponding statistical models---have suddenly increased by several orders of magnitude. Neither the observed information nor the Fisher information is easy to obtained for these big data sets. This paper introduces an information splitting technique to simplify the computation. After splitting the mean of the observed information and the Fisher information, an simpler approximate Hessian matrix for the log-likelihood can be obtained. This approximated Hessian matrix can significantly reduce computations, and makes the linear mixed model applicable for big data sets. Such a spitting and simpler formulas heavily depends on matrix algebra transforms, and applicable to large scale breeding model, genetics wide association analysis.Comment: arXiv admin note: text overlap with arXiv:1605.0764

Fabrication, characterization, and modeling of organic capacitors, Schottky diodes, and field effect transistors

The objectives of this project are to fabricate, characterize, and model organic microelectronic devices by traditional lithography techniques and Technology Computer Aided Design (TCAD). Organic microelectronics is becoming a promising field due to its number of advantages in low-cost fabrication for large area substrates. There have been growing studies in organic electronics and optoelectronics. In this project, several organic microelectronic devices are studied with the aid of experimentation and numerical modeling. Organic metal-insulator-metal (MIM) and metal-insulator-semiconductor (MIS) capacitors consisting of insulating polymer poly(4-vinylphenol) (PVP) have been fabricated by spin-coating, photo lithography, and reactive ion etching techniques. Based on the fabricated devices, the dielectric constant of the (PVP) is calculated to be about 5.6–5.94. The MIS capacitor consisting of organic semiconductor pentacene has been investigated. The hole concentration of pentacene is determined to be around 8 × 1016 cm −3. Schottky diodes consisting of aluminum and a layer of p-type semiconducting polymer poly[2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) have been fabricated. Based on the current-voltage (I-V) and capacitance-voltage (C-V) measurements, the temperature dependence of hole mobility in MEH-PPV has been extracted by the space-charge limited conduction (SCLC) model, from 300 to 400 K. Moreover, the value of the effective hole density for MEH-PPV has been determined to be 2.24 × 1017 cm−3. Numerical simulations have been carried out to identify the parameters which affect the performance of devices significantly. Organic n- and p-channel field-effect transistors (FETs) have been designed and fabricated. By using Naphthalene-tetracarboxylic-dianhydride (NTCDA) as an organic semiconductor, n-channel FETs have been fabricated and characterized. At room temperature, the device characteristics have displayed electron mobility of 0.016 cm2/Vs, threshold voltage of −32 V, and on/off ratio of 2.25 × 102. Pentacene, an organic semiconductor offering high device performance, has been employed to fabricate the p-channel FETs. At room temperature, the device characteristics have displayed hole mobility of 0.26 cm2/Vs, threshold voltage of −3.5 V, subthreshold slope of 2.5 V/decade, and on/off ratio of 105. The temperature and field dependence of mobility has been studied based on the experimental results. Based on numerical simulations, the influence of bulk traps has also been identified, and the field-dependent mobility model has been used to obtain more accurate simulation results. Furthermore, electrostatically assembled monolayer (poly(dimethyldiallylammonium chloride) (PDDA)) is introduced at the organic/insulator interface to improve the performance of the FETs. The efforts carried out in this work appear to be the first reported attempt at the investigation of the temperature dependence of mobility for the given organic devices, and the surface modification of organic FETs by electrostatically assembled monolayer

Physical configuration-based feedforward active noise control using adaptive second-order truncated Volterra filter

This paper presents a physical configuration-based feedforward active noise control scheme with an adaptive second-order truncated Volterra filter for point source cancellation in three-dimensional free-field acoustic environment. The inertial particle swarm optimization (PSO) algorithm is used as the parameter adjustment mechanism for tuning the coefficients of the adaptive Volterra filter. The first motivation of this paper is to provide a precise description of the relationship between the degree of cancellation and the physical distances between system components. The second motivation is to improve the cancellation performance in the presence of nonlinearities with the adaptive Volterra filter in light of the characteristics of sensing microphone and actuating loudspeaker. The reason for choosing the inertial PSO algorithm is that it can avoid the trap of local optima. The work thus presented makes two main contributions. The first is using the degree of cancellation as a function of the physical distances between system components to provide a quantitative analysis of system performance. The second is the application of the adaptive Volterra filter, which achieves improvements in the cancellation performance of the system under different physical configurations with a reasonable compromise with complexity. For consistency with the numerical analysis, several simulation experiments are conducted using MATLAB/Simulink

Effective Image Tampering Localization via Semantic Segmentation Network

With the widespread use of powerful image editing tools, image tampering becomes easy and realistic. Existing image forensic methods still face challenges of low accuracy and robustness. Note that the tampered regions are typically semantic objects, in this letter we propose an effective image tampering localization scheme based on deep semantic segmentation network. ConvNeXt network is used as an encoder to learn better feature representation. The multi-scale features are then fused by Upernet decoder for achieving better locating capability. Combined loss and effective data augmentation are adopted to ensure effective model training. Extensive experimental results confirm that localization performance of our proposed scheme outperforms other state-of-the-art ones