An Efficient Module for Full Adders in Quantum-dot Cellular Automata

Quantum-dot cellular automata (QCA), a new computing paradigm at nanoscale, may be a prospective alternative to conventional CMOS-based integrated circuits. Modular design methodology in QCA domain has not been widely investigated. In this paper, an efficient module with fault tolerance is proposed, which can be employed to fabricate three-input and five-input majority gates that are the fundamental primitives for designing circuits in QCA. With cells omission in the versatile module, various logic gates will be achieved, such as Nand-Nor-Inverter (NNI) gate and And-Or-Inverter (AOI) gate. Moreover, in order to seek out an efficient full adder, five various QCA full adders are designed and exhaustively compared in terms of area, complexity, latency, reliability and power dissipation and also compared with existing fault-tolerant full adders. Two simulation tools, QCADesigner and QCAPro, are utilized in the waveform simulations for verifying the correctness of proposed circuits and power consumption, respectively. The analysis results reveal that full adder V has significant improvements in contrast to its counterparts with above criteria. To test the practicability of full adder V, multi-bit adders will be designed in single-layer and compared with previous adders in terms of area, complexity and QCA cost, which proves the merits of our work.     

液体表面张力系数的实验研究

改变液体的浓度可以调控液体的表面张力系数,各种形状膜架的挂膜时间与液体表面张力系数存在着一定的关系,本文对于这两个方面进行了实验研究,得出了相应的结果.此外,溶液的温度和空气的流动对挂膜时间都会产生影响.     

Effects of locally resonant modes on underwater sound absorption in viscoelastic materials

Recently, by introducing locally resonant scatterers with spherical shape proposed in phononic crystals into design of underwater sound absorption materials, the low-frequency underwater sound absorption phenomenon induced by the localized resonances is observed. To reveal this absorption mechanism, the effect of the locally resonant mode on underwater sound absorption should be studied. In this paper, the finite element method, which is testified efficiently by comparing the calculation results with those of the layer multiple scattering method, is introduced to investigate the dynamic modes and the corresponding sound absorption of localized resonance. The relationship between the resonance modes described with the displacement contours of one unit cell and the corresponding absorption spectra is discussed in detail, which shows that the localized resonance leads to the absorption peak, and the mode conversion from longitudinal to transverse waves at the second absorption peak is more efficient than that at the first one. Finally, to show the modeling capability of FEM and investigate shape effects of locally resonant scatterers on underwater sound absorption, the absorption properties of viscoelastic materials containing locally resonant scatterers with ellipsoidal shape are discussed.     

Effect of preheating temperatures on microstructure and optical properties of Na-doped ZnO thin films by sol–gel process

The chemical composition, crystalline structure, surface morphology and photoluminescence spectra of Na-doped ZnO thin films with different heat treatment process were investigated by X-ray photoelectron spectroscopy, X-ray diffraction, atomic force microscopy and a fluorescence spectrometer. The results show that preferred orientation, residual stress, average crystal size and surface morphology of the thin films are strongly determined by the preheating temperature. The effects of preheating temperature on microstructure and surface morphology have been discussed in detail. The photoluminescence spectra show that there are strong violet & UV emission, blue emission and green emission bands. The violet & UV emission is ascribed to the electron transition from the localized level below the conduction band to the valence band. The blue emission is attributed to the electron transition from the shallow donor level of oxygen vacancies to the valence band, and the electron transition from the shallow donor level of interstitial zinc to the valence band. The green emission is assigned to the electron transition from the level of ionized oxygen vacancies to the valence band.     

Characterization of Cr‐doped Sb2Te3 films and their application to phase‐change memory

Phase‐change memory (PCM) is regarded as one of the most promising candidates for the next‐generation nonvolatile memory. Its storage medium, phase‐change material, has attracted continuous exploration. Along the traditional GeTe–Sb₂Te₃ tie line, the binary compound Sb₂Te₃ is a high‐speed phase‐change material matrix. However, the low crystallization temperature prevents its practical application in PCM. Here, Cr is doped into Sb₂Te₃, called Cr–Sb₂Te₃ (CST), to improve the thermal stability. We find that, with increase of the Cr concentration, grains are obviously refined. However, all the CST films exhibit a single hexagonal phase as Sb₂Te₃ without phase separation. Also, the Cr helps to inhibit oxidation of Sb atoms. For the selected film CST_10.5, the resistance ratio between amorphous and crystalline states is more than two orders of magnitude; the temperature for 10‐year data retention is 120.8 °C, which indicates better thermal stability than GST and pure Sb₂Te₃. PCM cells based on CST_10.5 present small threshold current/voltage (4 μA/0.67 V). In addition, the cell can be operated by a low SET/RESET voltage pulse (1.1 V/2.4 V) with 50 ns width. Thus, Cr–Sb₂Te₃ with suitable composition is a promising novel phase‐change material used for PCM with high speed and good thermal stability performances. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Fractional Fokker-Planck Equation with Space and Time Dependent Drift and Diffusion

In this paper, we aim to answer the question proposed by Magdziarz (Stoch. Proc. Appl. 119:3238?C3252, 2009), i.e. we investigate the solution of an anomalous diffusion equation with time and space dependent force and diffusion coefficient. First, we try to find the stochastic representation of this equation, which means the PDF of this stochastic process is rightly the solution of the equation we aim to solve. Then, we also simulate the sample paths of the stochastic process. At last, taking advantage of the stochastic representation method, we employed Monte Carlo method to approximate the solution of the mentioned equation.     

Theoretical and Experimental Study of the Diffraction Intensity of Gradient Refractive-Index Lenses

We develop the wave-optics approach for calculating the diffraction distribution of gradient refractiveindex lenses and observing the diffraction pattern of gradient refractive-index lenses in the experiments. The results of our calculation are in good agreement with the experimental results obtained. We show that the diffraction can be regarded as a method to check the quality of the refractive-index distributions of gradient refractive-index lenses.     

A novel image tamper localization and recovery algorithm based on watermarking technology

In this paper, an effective self-embedding fragile watermarking scheme is presented. The watermark is generated by encoding the DCT coefficients of each 2 × 2 block and embedded into another block according to the block mapping. A non-linear chaotic sequence is used for generating the block mapping which can enhance the security of the algorithm. An improved tamper localization and recovery algorithm are performed. The experiment results show that the watermarked image has a high average peak signal-to-noise ratio. Furthermore, the tamper region can be successfully localized and exactly recovered, even if for the content-only tampering.     

s-Parameterized phase space distribution for describing no counts registered on a photonic detector

By introducing the generalized Wigner operator for s-parameterized quasiprobability distribution and employing the technique of integration within ordered product (IWOP) of operators (normally ordered, Weyl ordered or antinormally ordered), we derive two new quantum-mechanical formulas for describing no counts registered on a photonic detector when a light field’s density operator ρ is known, one involves ρ’s s-parameterized distribution function, and the other involves ρ’s coherent state mean value, when these information is known then using the new formulas to calculate no-photocount would be convenient.