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The dual-scrambling scheme that combines position transformation and bit-plane transformation is a popular image encryption scheme. However, such schemes need more key information, and the encryption and decryption processes are complicated. In addition, the existing quantum image dual-scrambling schemes mainly deal with square images. In this paper, we propose a hybrid scrambling encryption scheme for multi-mode quantum image representation (MQIR) images based on random permutation, in which the H × W quantum image is represented in MQIR. A random number generator factor s uniquely associates one of the random permutations of integers from 1 to a positive integer, so as to hybrid scramble both the pixel position and the binarized position of each pixel value. Meanwhile, the quantum circuits and some examples of scrambling are given. Furthermore, various analyses of the performance of this scheme were conducted, including effectiveness, key space, and computational complexity. By modifying the random generation factor to construct multiple binary grayscale images, the simulated results on the IBM Quantum Cloud platform demonstrate that the proposed quantum image encryption scheme is effective. In comparison to existing quantum image dual scrambling schemes, it is both simple and effective, offering a large key space, lower computational complexity, and applicability to non-square quantum images. [ABSTRACT FROM AUTHOR]

Nonlinear surface waves propagating along a single interface between a linear metamaterial and a nonlinear antiferromagnet are theoretically studied. The frequency response of transverse-magnetic-polarized waves covering the frequency range from the microwave to the infrared regime is investigated in detail. We find that the waveguide supports soliton-like surface waves with low-pass response in the microwave range and bandpass response in the microwave and infrared ranges. The bandwidth is a function of the nonlinearity and can be tuned by controlling the incident wave power. [ABSTRACT FROM AUTHOR]

The viscometric behavior of laponite and bentonite suspensions at different concentrations in shear flow is studied. It is discovered that in the equilibrium state, a master curve of viscosity can be constructed when the applied shear stress is normalized by the respective suspension's yield stress. The interparticle interaction controlling the yield behavior at the gel state also dominates the behavior of particles at the equilibrium flowing state. A constitutive framework is developed to describe the master curve of viscosity as a function of the shear stress normalized by the yield stress. Based on the proposed model, the effect of concentration on the viscosity of clay suspensions can be estimated via their yield stress. [ABSTRACT FROM AUTHOR]

The nonlinear optical absorption in a three-subband step asymmetric semiconductor quantum well driven by a strong terahertz (THz) field is investigated theoretically by employing the intersubband semiconductor-Bloch equations. We show that the optical absorption spectrum strongly depends on the intensity, frequency, and phase of the pump THz wave. The strong THz field induces THz sidebands and Autler-Townes splitting in the probe absorption spectrum. Varying the pump frequency can bring not only the new absorption peaks but also the changing of the energy separation of the two higher-energy levels. The dependence of the absorption spectrum on the phase of the pump THz wave is also very remarkable. [ABSTRACT FROM AUTHOR]

Numerous laboratory-scale physical experiments and numerical simulations have been carried out to explore the shoaling dynamics of internal solitary waves (ISWs) on slope topographies. Detailed features during wave breaking have been investigated under relatively low Reynolds numbers, but for real ocean-scale or lake-scale scenarios with a much higher Reynolds number, laboratory-scale modeling is inadequate to capture the three-dimensional turbulent characteristics in the wave shoaling process. As a result, a three-dimensional large-eddy simulation (LES) is performed in the present study to investigate the shoaling process of the elevation-typed ISWs traveling on uniform slopes in a two-layer fluid system. Scale effects due to the Reynolds numbers (varied from 103 to 105) and three-dimensional characteristics during wave shoaling are also explored and discussed. Detailed ISW-slope interaction dynamics, including the typical shoaling features, the characteristics of internal boluses, and both the velocity field and the energy transformation, are systematically obtained and analyzed. It is found that, while reaching the maximum vertical displacement (i.e., maximum run-up height), the frontal part of the heavier lower-layer fluid can evolve into the internal bolus if the internal Iribarren number, Ir, defined as the ratio of the topographic slope and the square root of the incident wave steepness, is less than 0.65. The maximum wave-induced velocities and energy loss are also well related to Ir. Empirical regressed equations for seven important physical parameters during the shoaling process are also proposed. The extreme velocities, wave energy loss, and three-dimensionality of the flow field are all identified to be very sensitive to Reynolds numbers, indicating that traditional two-dimensional laboratory-scale modeling tools may be insufficient to accurately capture the shoaling mechanisms of the ISWs of elevation type. [ABSTRACT FROM AUTHOR]

Buoyant plumes from different river mouths extensively collide and converge in coastal areas worldwide, but these interactions and dynamics have not been extensively studied. Plume-to-plume interactions have been mainly investigated using hydrostatic simulations so far, which have limitations in terms of flow structure resolution. This study conducts a comprehensive investigation on both hydrostatic and nonhydrostatic simulations to understand the dynamics of the frontal collision of two buoyant plumes. The results show that nonhydrostatic simulations distinctly differ from hydrostatic simulations. Moreover, nonhydrostatic simulations yield plume evolutions that are more in line with the physical reality and field observations in terms of the flow structures. Nonhydrostatic simulations reveal bore-like structures at the rear of the plume front, clearly exhibiting their effects on the shape evolution and interfacial entrainment. Furthermore, the existing classification of plume collision is reexamined, and the basic dynamics and collision types under nonhydrostatic simulations are elucidated. Additionally, dynamic pressure characteristics are investigated, which suggests that dynamic pressure is the key to the generation and evolution of vortex structures. [ABSTRACT FROM AUTHOR]

Simultaneous existence of solute gradients along with temperature gradients in a double diffusive system is favorable to the onset of salt finger convection and this phenomenon has been investigated for several decades due to its efficient mixing mechanism. However, relatively few works were focused on the double diffusive process through a fluid-saturated porous interface (FPI), which could be applied in a variety of scenarios such as the directional solidification of concentrated alloys or mixing zones in coastal freshwater aquifers. In this paper, we consider the evolution of double-diffusive salt finger through FPI with a single-domain approach adopted for the solution of flow in a composite region made up of a fluid layer overlying a porous layer. Comparisons with existing numerical results show great agreement and demonstrate that flows through a fluid–porous system can be predicted with good accuracy by the proposed method. Several cases spanning a range of initial buoyancy ratio N 0 from 2 to 7 are conducted to study the structure and behavior of salt finger together with key issues being focused on the effect of initial buoyancy ratio on flux variations. Differing from in stratified fluid layers, salt finger through FPI shows an asymmetric structure in which the growth rate in the fluid layer is much greater and the finger column in the porous layer presents a squarer shape. It is found that under the condition of low initial buoyancy ratios, the potential energy stored in the unstable stratification of salinity converted more into kinetic energy, which enhances the mixture of heat and masses in the vertical direction. [ABSTRACT FROM AUTHOR]

The change of the rheological behavior of a bentonite suspension with the gap of the parallel-plate geometry in a rotational rheometer is investigated. An obvious gap-dependent behavior is found in both the gel and flowing states, based on which it is found that slip at the boundary plays an important role in the viscometric measurement at low shear rates, as well as in the small amplitude oscillatory shear experiment; shear banding is considered to take place at the vicinity of the yielding point, as well as in flows at low shear rates if the boundary slip is suppressed by using rough plates. Furthermore, relaxation behavior, similar to that of a polymeric system, is observed. The motion of the gel structure is slower with increasing gap, indicating a larger size of the networking structure. This is also the origin for the decrease of the yield stress observed with increasing gap. [ABSTRACT FROM AUTHOR]

Resonance Raman spectra were obtained for 2,5-di-iodothiophene in cyclohexane solution with excitation wavelengths in resonance with its A-band absorption. These spectra indicate that the Franck–Condon region photodissociation dynamics have multidimensional character with motion mostly along the nominal symmetric C2C3/C4C5 stretch ν2 (1388 cm-1) of the thienyl ring and this is accompanied by motions along the nominal symmetric CSC stretch ν6 (640 cm-1), the nominal symmetric C[Single_Bond]I stretch ν7 (187 cm-1), the nominal antisymmetric CSC stretch ν19 (728 cm-1), the nominal antisymmetric C2C3/C4C5 stretch ν16 (1497 cm-1), the nominal C3C4 stretch ν3 (1286 cm-1) and four other vibrational modes. A preliminary resonance Raman intensity analysis was done and the results for 2,5-di-iodothiophene were compared to previous results for 2-iodothiophene and di-iodomethane to discuss the mechanism of the symmetric breaking in the initial A-band photodissociation dynamics of 2,5-di-iodothiophene and 2-iodothiophene. [ABSTRACT FROM AUTHOR]

Sb-doped ZnO films were fabricated on c-plane sapphire using the pulsed laser deposition method and characterized by Hall effect measurement, X-ray photoelectron spectroscopy, X-ray diffraction, photoluminescence, and positron annihilation spectroscopy. Systematic studies on the growth conditions with different Sb composition, oxygen pressure, and post-growth annealing were conducted. If the Sb doping concentration is lower than the threshold ∼8 × 1020 cm−3, the as-grown films grown with an appropriate oxygen pressure could be n∼4 × 1020 cm−3. The shallow donor was attributed to the SbZn related defect. Annealing these samples led to the formation of the SbZn-2VZn shallow acceptor which subsequently compensated for the free carrier. For samples with Sb concentration exceeding the threshold, the yielded as-grown samples were highly resistive. X-ray diffraction results showed that the Sb dopant occupied the O site rather than the Zn site as the Sb doping exceeded the threshold, whereas the SbO related deep acceptor was responsible for the high resistivity of the samples. [ABSTRACT FROM AUTHOR]

The dielectric properties of CaCu3Ti4O12, Ba(Fe1/2Nb1/2)O3, and Sr(Fe1/2Nb1/2)O3 giant permittivity ceramics were evaluated at microwave frequencies using a modified resonant cavity method. In the frequency range between 3.4 and 9.5 GHz, the permittivities of the three ceramics were around 84.6, 43.9, and 40.4 at 20 °C and were nearly independent of frequency. The dielectric losses decreased and the Qf values increased significantly with increasing frequency. The temperature dependence of the dielectric properties was also investigated at about 6.02 GHz. With increasing temperature from -60 °C to 80 °C, the permittivities of CaCu3Ti4O12, Ba(Fe1/2Nb1/2)O3, and Sr(Fe1/2Nb1/2)O3 ceramics varied nearly linearly, and the corresponding temperature coefficients of permittivity were -700, 175, and 164 ppm/ °C, respectively. [ABSTRACT FROM AUTHOR]

The crystalline structure and dielectric properties of Sm1.5Sr0.5NiO4 ceramics are presented. The present ceramics is refined as orthorhombic Bmab phase and the orthorhombic strain may change the statue of charge ordering. The temperature-stable giant dielectric constant (∼100 000) with low dielectric loss of ∼0.1 is observed at frequency up to 5 MHz over a broad range of temperature (150–500 K) and frequency (100 kHz–5 MHz). The grain interior should be the dominative factor which contributes the giant dielectric response in the present ceramics after the equivalent circuit fitting, and the thermal activated small polaronic hopping related to the charge ordering is that factor. Compared to other giant dielectric materials, the present materials have a great potential in the practical application, especially for the high frequency application. [ABSTRACT FROM AUTHOR]

Dielectric relaxations of charge-ordered Ln1.5Sr0.5NiO4 (Ln=La and Nd) ceramics were investigated over a broad temperature range. The giant dielectric constant (over 70 000) with a low dielectric loss of ∼0.1 was determined at high frequencies (up to 5 MHz) over a broad temperature range. There are two dielectric relaxations in the vicinity of charge ordering temperatures. The thermal activated small polaronic hopping between two charge ordering temperatures should contribute to the giant dielectric response in the present ceramics. Compared to other giant dielectric constant materials, the present materials have the notable advantage for high frequency applications. [ABSTRACT FROM AUTHOR]

A correction is presented for Fig. 4 in the article "Giant dielectric response in two-dimensional charge-ordered nickelate ceramics," which is in volume 104 of this journal.

Salt fingers as a mixing mechanism in the ocean have been investigated for several decades, together with a key issue being focused on their convective evolution and flux ratio variation. However, related studies on tilting fingers in the ocean produced by shear flow have been ignored by previous researchers. In this paper, a 2-D numerical model is presented to study the evolution of the double-diffusion salt finger in a two-layer thermohaline system with laminar shear flow. The model is divided into a steady-state solver and double-diffusion convection system, aimed to reveal the effect of shear flow on salt fingers and analyze the mechanism behind the shear and fingers. Several cases are conducted for Re = 0 ∼ 900 to study the evolution of salt fingers in a laminar shear flow and the variation of salt flux with Re. The results show that salt fingers exist and tilt in the presence of laminar shear flow. The mass transport in the vertical direction is weakened as the Reynolds number increases. An asymmetric structure of the salt finger is discovered and accounts for the morphological tilt and salt flux reduction. [ABSTRACT FROM AUTHOR]

We experimentally demonstrate electrical tuning of plasmonic mid-infrared absorber resonances at 4 μm wavelength. The perfect infrared absorption is realized by an array of gold nanostrip antennas separated from a back reflector by a thin dielectric layer. An indium tin oxide active layer strongly coupled to the optical near field of the plasmonic absorber allows for spectral tunability. [ABSTRACT FROM AUTHOR]