A blind color image watermarking based on DC component in the spatial domain

Color image watermarking has become essential and important copyright protection or authentication scheme. It is noted that most of the existing color image watermarking algorithms are performed only in the single domain (spatial domain or frequency domain), and not to integrate these merits of the different domains. By utilizing the generating principle and distribution feature of the direct current (DC) coefficient, a novel blind watermarking algorithm is proposed for color host images in this paper. Firstly, the Y luminance of host image is divided into 8 × 8 sub-blocks and the DC coefficients of each block are directly calculated in the spatial domain without DCT transform. Secondly, according to the watermark information and the quantization step, the DC coefficients are calculated and their increments are further utilized to modify directly the values of all pixels in the spatial domain instead of the DCT domain to embed watermark. When watermark extraction, only the watermarked image and the quantization step are needed in the spatial domain. Experimental results show that the proposed method not only can resist both traditional signal processing attacks and geometric attacks, but also has more efficient in computational complexity. Comparisons also demonstrate the advantages of the method.     

InGaAsP quantum-wells saturable absorber for diode-pumped passively Q-switched 1.3-μm lasers

We demonstrate the first use of InGaAsP quantum wells as a saturable absorber in the Q-switching of a diode-pumped Nd-doped 1.3 μm laser. The barrier layers of the InGaAsP quantum-well device are designed to be a strong absorber for the suppression of the transition channel at 1.06 μm. With an incident pump power of 1.8 W, an average output power of 160 mW with a Q-switched pulse width of 19 ns at a pulse repetition rate of 38 kHz was obtained. PACS 42.60.Gd; 42.55.Xi; 42.65.Re     

重力场中的熵产生研究

重力场中的大气处于非平衡态，其温度是空间的函数，不同的等温面之间要产生热流，从而改变熵的空间分布。本文推导出重力场中的熵产生公式，并描绘出熵产生随高度变化的近似曲线。     

22Na(p,γ)23Mg反应的实验研究

讨论了目前有关²²Na(p,γ)²³Mg反应的实验研究工作,结合兰州放射性束流线上的放射性束流²³Al的β⁺延发质子衰变实验的测量结果,给出了²³Al延发衰变的质子能谱,并比较了近期实验给出的相关能级的自旋、宇称值,正是由于这种自旋、宇称和能级部分宽度的不确定性,导致了反应率计算的不确定性.计算了同位旋相似态的共振强度.对于测量到的新的延发衰变能级E_d=8.916MeV,由于没有相应的能级宽度值,实验仅给出其相对共振强度值.     

Fabrication of textured KNNT ceramics by reactive template grain growth using NN templates

Lead-free non-stoichiometric (K_0.470Na_0.545)(Nb_0.55Ta_0.45)O₃ (KNNT) textured ceramics were prepared by a reactive templated grain growth method using NaNbO₃ (NN) templates. The Plate-like NaNbO₃ (NN) templates were synthesized from bismuth layer-structured Bi_2.5Na_3.5Nb₅O₁₈ (BNN) particles by a topochemical microcrystal conversion (TMC) method. Using 5 wt% of NN templates, textured KNNT ceramics were fabricated, and their crystal structure, microstructure, dielectric and piezoelectric properties were compared with non-textured KNNT ceramics prepared by a conventional solid state reaction method. The textured KNNT ceramics exhibited high grain orientation and high dielectric constant. In addition, piezoelectric properties of textured KNNT ceramics were improved, giving a high piezoelectric coefficient d₃₃ = 390 pC/N and piezoelectric coupling coefficient k_p = 0.60.     

Polyvinylpyrrolidone (PVP) assisted single‐step synthesis of kesterite Cu2ZnSnS4 nanoparticles by solvothermal process

Quaternary kesterite‐type Cu₂ZnSnS₄ (CZTS) nanoparticles (NPs) were successfully synthesized by a single‐step solvothermal process. Semiconductor CZTS nanoparticles were obtained from ethylene glycol (EG) and CZTS precursor after solvothermal process at 180 °C for 30 h in polyvinylpyrrolidone (PVP) medium. The synthesized CZTS NPs were further annealed at 450 °C in nitrogen atmosphere and used for further characterizations. The CZTS NPs were characterized using X‐ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), micro Raman spectroscopy, high resolution transmission electron microscopy (HRTEM) and X‐ray photoelectron spectroscopy (XPS). The optical properties of the CZTS NPs were recorded by UV–vis absorption spectroscopy. The results showed that the synthesized CZTS nanoparticles are kesterite‐type CZTS, with good crystallinity and a stoichiometric composition. Moreover, the prepared nanoparticles have a size ranging from 5–7 nm and a band gap of ～1.5 eV.

     

Response of bilateral breasts to the endogenous hormonal fluctuation in a menstrual cycle evaluated using 3D MRI

The normal breast tissue responds to the fluctuation of endogenous hormones during a menstrual cycle (MC) and shows changes in breast density. The changes between left and right breasts of the same women were compared to evaluate the symmetrical response. Twenty-four healthy women were recruited in this study. Four weekly magnetic resonance imaging (MRI) studies were performed during one MC. A computer algorithm was used to segment the breast and the fibroglandular tissue to measure the fibroglandular tissue volume (FV) and three morphological parameters: circularity, convexity and irregularity. The coefficient of variation (CV) for each parameter measured among four MRI studies was calculated; also, the maximal percent change between two MRI studies that show the highest and the lowest FV was calculated. These parameters measured from left and right breasts were compared using Pearson correlation.     

A proposed direct measurement of cross section at Gamow window for key reaction ~(19)F( p,α)~(16)O in Asymptotic Giant Branch stars with a planned accelerator in CJPL

In 2014, the National Natural Science Foundation of China(NSFC) approved the Jinping Underground Nuclear Astrophysics laboratory(JUNA) project, which aims at direct cross-section measurements of four key stellar nuclear reactions right down to the Gamow windows. In order to solve the observed fluorine overabundances in Asymptotic Giant Branch(AGB) stars, measuring the key ~(19)F( p,α)~(16)O reaction at effective burning energies(i.e., at Gamow window) is established as one of the scientific research sub-projects. The present paper describes this sub-project in details, including motivation, status, experimental setup, yield and background estimation, aboveground test, as well as other relevant reactions.     

Character and Dimension Formulae for Queer Lie Superalgebra

We study transmission problems with free interfaces from one random medium to another. Solutions are required to solve distinct partial differential equations, \({{\rm L}_{+}}\) and \({{\rm L}_{-}}\), within their positive and negative sets respectively. A corresponding flux balance from one phase to another is also imposed. We establish existence and \({L^{\infty}}\) bounds of solutions. We also prove that variational solutions are non-degenerate and develop the regularity theory for solutions of such free boundary problems.