Geomorphic Evolution of Radial Sand Ridges in the South Yellow Sea Observed from Satellites

The radial sand ridges consist of more than 70 sand ridges that are spread out radially on the continental shelf of the South Yellow Sea. As a unique geomorphological feature in the world, its evolution process and characteristics are crucial to marine resource management and ecological protection. Based on the multi-source remote sensing image data from 1979 to 2019, three types of geomorphic feature lines, artificial coastlines, waterlines, and sand ridge lines were extracted. Using the GIS sequence analysis method (Digital Shoreline Analysis System (DSAS), spatial overlay analysis, standard deviational ellipse method), the evolution characteristics of the shoreline, exposed tidal flats, and underwater sand ridges from land to sea were interpreted. The results demonstrate that: (1) The coastline has been advancing towards the sea with a maximum advance rate of 348.76 m/a from Wanggang estuary to Xiaoyangkou Port. (2) The exposed tidal flats have decreased by 1484 km2 including the reclaimed area of 1414 km2 and showed a trend of erosion in the north around Xiyang channel and deposition in the southeast around the Gaoni and Jiangjiasha areas. (3) The overall sand ridge lines showed a trend of gradually moving southeast (135°), and the moving distance is nearly 4 km in the past 40 years. In particular, the sand ridge of Tiaozini has moved 11 km southward, while distances of 8 km for Liangyuesha and 5 km for Lengjiasha were also observed. For the first time, this study quantified the overall migration trend of the RSRs. The imbalance of the regional tidal wave system may be one of the main factors leading to the overall southeastward shift of the radiation sandbanks.

Between Harmonic Crystal and Glass: Solids with Dimpled Potential-Energy Surfaces Having Multiple Local Energy Minima

Solids with dimpled potential-energy surfaces are ubiquitous in nature and, typically, exhibit structural (elastic or phonon) instabilities. Dimpled potentials are not harmonic; thus, the conventional quasiharmonic approximation at finite temperatures fails to describe anharmonic vibrations in such solids. At sufficiently high temperatures, their crystal structure is stabilized by entropy; in this phase, a diffraction pattern of a periodic crystal is combined with vibrational properties of a phonon glass. As temperature is lowered, the solid undergoes a symmetry-breaking transition and transforms into a lower-symmetry phase with lower lattice entropy. Here, we identify specific features in the potential-energy surface that lead to such polymorphic behavior; we establish reliable estimates for the relative energies and temperatures associated with the anharmonic vibrations and the solid–solid symmetry-breaking phase transitions. We show that computational phonon methods can be applied to address anharmonic vibrations in a polymorphic solid at fixed temperature. To illustrate the ubiquity of this class of materials, we present a range of examples (elemental metals, a shape-memory alloy, and a layered charge-density-wave system); we show that our theoretical predictions compare well with known experimental data.

Band-gap structure of the spectrum of the water-wave problem in a shallow canal with a periodic family of deep pools

We consider the linear water-wave problem in a periodic channel $$\Pi ^h \subset {{\mathbb {R}}}^3$$ Π h ⊂ R 3 , which is shallow except for a periodic array of deep potholes in it. Motivated by applications to surface wave propagation phenomena, we study the band-gap structure of the essential spectrum in the linear water-wave system, which includes the spectral Steklov boundary condition posed on the free water surface. We apply methods of asymptotic analysis, where the most involved step is the construction and analysis of an appropriate boundary layer in a neighborhood of the joint of the potholes with the thin part of the channel. Consequently, the existence of a spectral gap for small enough h is proven.

QUBO Formulations for a System of Linear Equations

With the advent of quantum computers, many quantum computing algorithms are being developed. Solving linear systems is one of the most fundamental problems in almost all of science and engineering. Harrow-Hassidim-Lloyd algorithm, a monumental quantum algorithm for solving linear systems on the gate model quantum computers, was invented and several advanced variations have been developed. For a given square matrix A∈R(n×n) and a vector b∈R(n), we will find unconstrained binary optimization (QUBO) models for a vector x∈R(n) that satisfies Ax=b. To formulate QUBO models for a linear system solving problem, we make use of a linear least-square problem with binary representation of the solution. We validate those QUBO models on the D-Wave system and discuss the results. For a simple system, We provide a python code to calculate the matrix characterizing the relationship between the variables and to print the test code that can be used directly in D-Wave system.

The Cranio-Sacral Approach for Defining Embodied “Coherence”

The premise of this book is that applying principles of electromagnetic (EM) resonant coherence to the media field is the key to generating a more harmonious culture. The advent of new types of sensors, quite affordable and increasingly sensitive, now provides an easy way to measure frequencies and rhythms of the body and to create applications that visualize brain waves and waves extracted from cardiac parameters. The term “coherence” used in physics defines the correlations of a wave system. More recently, this term has been used increasingly to define an inner state of “centering” and harmony that presents as relaxation, stress management, deep meditation, and state of transcendent bliss. The craniosacral approach provides important information on how that can be achieved.

Study on resistance characteristics of submarine near water surface

The submarine is usually affected by free surface and the navigation resistance increases when sailing near the surface. In order to study the specific resistance characteristics of submarine sailing near the surface, the SUBOFF with appendages was taken as the research object, and the calculation model was built based on Star CCM+ fluid simulation software, and the resistance coefficients under different submarine depths and speeds were calculated. Through comparative analysis, the influence of the depth and speed of the submarine on the resistance components was obtained, and the cause of the formation was analyzed. The results show that the influence of the depth of submarine on friction resistance coefficient is small in general. With the increase of the depth of the submarine, the pressure resistance coefficient decreases, and the wave amplitude decreases. The shear wave of Kelvin wave system is more obvious and the effect of scattering is weakened, which is of great significance for the study of submarine concealment. With the increase of speed, friction resistance coefficient decreases, the overall change trend of pressure resistance coefficient is first increased and then decreases. The interference effect between free surface and hull increases first and then decreases at each depth. The wave shape changes and resistance results mutually confirm. The free surface mainly generates waves by interacting with the hull, which affects the resistance characteristics of the submarine. The interference effect is greatly affected by the depth and speed of the submarine.