A Novel Quantum Visual Secret Sharing Scheme

Inspired by Naor et al.'s visual secret sharing (VSS) scheme, a novel n out of n quantum visual secret sharing (QVSS) scheme is proposed, which consists of two phases: sharing process and recovering process. In the first process, the color information of each pixel from the original secret image is encoded into an n-qubit superposition state by using the strategy of quantum expansion instead of classical pixel expansion, and then these n qubits are distributed as shares to n participants, respectively. During the recovering process, all participants cooperate to collect these n shares of each pixel together, then perform the corresponding measurement on them, and execute the n-qubit XOR operation to recover each pixel of the secret image. The proposed scheme has the advantage of single-pixel parallel processing that is not available in the existing analogous quantum schemes and perfectly solves the problem that in the classic VSS schemes the recovered image has the loss in resolution. Moreover, its experiment implementation with the IBM Q is conducted to demonstrate the practical feasibility.Comment: 19 pages, 13 figure

Study of the Key Mechanical Properties of Welded Hollow Spherical Joints after Uniform Corrosion

The welded hollow spherical joint is the most common form of the spatial grid structure, but the corrosion treatment at the joint is difficult. There are many corrosion problems of the welded hollow spherical joint in the actual structure, which brings hidden problems to structural safety. To study the effects of uniform corrosion on the key mechanical properties of welded hollow spherical joints, the joint refinement FEM in one typical size is built considering the effect of uniform corrosion through the method of the element birth and death, and the tensile, compressive, and bending performance of the FEM has been analyzed. Based on the analysis results, the relation curves between the three bearing capacities of the welded hollow spherical joint and the uniform corrosion degree are given. The results show that the influence of early corrosion on the joint tensile and compressive performance is not obvious. After corrosion to a certain extent, the loss of tensile and compressive capacity has a significant linear relationship with the degree of corrosion, and the loss of bending capacity has a significant quadratic curve relationship with the degree of corrosion from the initial stage. This study can provide a theoretical reference for a better understanding of the mechanical properties of welded hollow spherical joints in one typical size after corrosion to evaluate structural safety

XANES investigation of the local structure of Co nanoclusters embedded in Ag

Ion-implanted cobalt atoms into a silver matrix with a layer thickness of about 20 nm were studied by x-ray absorption near-edge spectroscopy (XANES) at the Co $K$ edge. Full multiple scattering ab initio calculations of Co XANES at the $K$ edge provide a phase fingerprint to distinguish the Co structure of samples prepared at different doses and annealing temperatures. The bcc Co phase is formed for the as-prepared sample with 6 at. % and the fcc Co phase is formed at the expense of the bcc phase for the sample with 12 at. % after annealing at $400\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}.

XANES investigation of the local structure of Co nanoclusters embedded in Ag. Phys

Ion-implanted cobalt atoms into a silver matrix with a layer thickness of about 20 nm were studied by x-ray absorption near-edge spectroscopy ͑XANES͒ at the Co K edge. Full multiple scattering ab initio calculations of Co XANES at the K edge provide a phase fingerprint to distinguish the Co structure of samples prepared at different doses and annealing temperatures. The bcc Co phase is formed for the as-prepared sample with 6 at. % and the fcc Co phase is formed at the expense of the bcc phase for the sample with 12 at. % after annealing at 400°C

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Blind sorting of multiple FH signals in synchronous networking under underdetermined conditions

In order to improve the performance of network sorting under underdetermined conditions, this paper proposes a blind sorting method for multiple frequency hopping (FH) signals in synchronous networking based on the blind source separation. Firstly, the short-time Fourier transform is performed on the multiple FH signals received by the L-shaped antenna array, and the time-frequency map is denoised by using the adaptive threshold of the SNR. Then the time-frequency single-source-point (SSP) detection algorithm is used to get effective time-frequency SSP. The FH signal is segmented on the time-frequency diagram to detect the frequency hopping time. In a certain hopping time, carrier frequency and its corresponding mixing matrix is estimated. Finally, the DOA information of the FH signal is calculated according to the carrier frequency information and the estimated mixing matrix, and the multiple FH signals are sorted according to the DOA information. Theoretical research shows that multiple FH signals can be separated by only three receiving antennas, and simulation results verify the effectiveness of the proposed algorithm

Research on Microbial Community Structure in Different Blocks of Alkaline–Surfactant–Polymer Flooding to Confirm Optimal Stage of Indigenous Microbial Flooding

The microbial communities associated with alkaline–surfactant–polymer (ASP)-flooded reservoirs have rarely been investigated. In this study, high-throughput sequencing was used to analyse the indigenous microbial communities in two different blocks, the water flooding after the alkaline–surfactant–polymer flooding block and the alkaline–surfactant–polymer flooding block, and to ascertain the optimal stage for the implementation of indigenous microbial oil recovery technology. The different displacement blocks had significant effects on the indigenous microbial community at the genus level according to an alpha diversity analysis and community composition. In water flooding after alkaline–surfactant–polymer flooding, the dominant genus of Pseudomonas exceeded 30%, increasing to 52.1% in alkaline–surfactant–polymer flooding, but alpha diversity decreased. Through a co-occurrence network analysis, it was found that the complexity of the water flooding after alkaline–surfactant–polymer flooding was higher than that of alkaline–surfactant–polymer flooding. This means that the water flooding ecosystem after alkaline–surfactant–polymer flooding was more stable and less susceptible to external environmental influences. In addition, there were significant differences in the functional redundancy of microbial communities in different blocks. In summary, the optimal stage for implementing local microbial oil recovery technology may be water flooding after alkaline–surfactant–polymer flooding

Experimental Study on Proppant Migration in Fractures Following Hydraulic Fracturing

Complex fracture technology is key to the successful development of unconventional oil and gas reservoirs, such as shale. Most current studies focus on how to improve the complexity of the fracture network. It is still unclear whether proppant can enter the branch fractures at all levels after the formation of complex fractures. The effects of construction displacement, proppant particle size, proppant density, fracturing fluid viscosity, sand ratio, and other factors on proppant migration in single fractures and complex fractures were studied using an experimental device independently developed by the laboratory. The results show that the lowest point height of the sandbank and the equilibrium height of the sandbank are directly proportional to the particle concentration and density, respectively, and inversely proportional to the displacement and fracturing fluid viscosity. The equilibrium time of the sandbank is inversely proportional to the displacement, particle concentration, and density, respectively, and proportional to the viscosity of the fracturing fluid. Under the same experimental conditions, the larger the branch angle, the smaller the height of the main/secondary fracture sandbank. In the design of the fracturing process, fracturing fluid with varying viscosities and proppant with different densities should be selected according to the formation conditions and fracturing targets. In the face of long fracture lengths, the combination of low-viscosity fracturing fluid with an appropriate viscosity and low-density proppant can meet the goal of placing proppant over long distances and effectively supporting fractures over extended lengths. Subsequently, high-density proppant or reduced construction displacement are adopted to usefully support fractures in the near-wellbore area. The results of this paper can provide theoretical support for proppant selection and fracturing program design