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This paper presents a numerical study of erosion–slippage failure of soil between piles caused by underground pipe leaking using the coupled CFD–DEM (computational fluid dynamics–discrete element method) approach. By tracking the change in particles migration and flow fluid during numerical simulation, the development mechanism of erosion–slippage failure is clarified on both microscopic and macroscopic scale. Three stages during this failure (initial, developing and failing) are proposed, and the definition of critical water pressure at leaking hole is confirmed by the comparison of particles and fluid field. Four crucial factors for soil to resist erosion–slippage failure are discussed: pile spacing, degree of density, soil–pile friction coefficient and soil gradation. Pile spacing has the most obvious influence on anti-erosion ability of soil. The degree of density determines whether the erosion–slippage failure happens in an instantaneous way or a continuous way. The increase in friction coefficient can enhance the resistance of soil to erosion to small extent. Soil gradation shows a great influence on migration of fine particles and strength of soil structure.

In this study, a dynamic grid mathematical model of scanning electrodeposition coupled with electric field, flow field, temperature field and concentration field was established. The transient distribution of multiple physical fields with different current densities (I was 0.075–0.275 A) and the growth of the coating were investigated. The preparation, morphology characterization and performance testing of nickel-based coatings were carried out. The results showed that the transient distribution of multiple physical fields reflected the deposition rule of the coating, and explains the deposition phenomenon of the coating with an “arch-shaped” distribution in the test. With the increase of current, the thickness of the coating and the degree of the arch increased. The numerical solution was consistent with the experimental law. The hardness, wear resistance and corrosion resistance of the coating increased first and then decreased. When I was 0.175 A (current densities was 700 A/m2), the maximum hardness of the nickel-based coating was 668.88 HV0.1, the minimum wear scar area was 1144.74 μm2, and the maximum equivalent resistance was 10,960 Ω. The temperature and concentration fields had little influence on the deposition process, and changes were only observed on the deposition surface. Electric and flow field distributions had greater influences on the deposition process, were the main reason for “arch-shaped” distribution.

Since the printing quick response (QR) code can be easily produced and duplicated as a potential tool for cybercriminals, QR code security has been a hotly debated issue across globe. Here we demonstrate a floating QR code device based on the moiré principle which has the advantage of displaying an appealing three-dimensional (3D) effect and privacy protection. In the imaging system, the microlens array (MLA) contributes to efficiently sampling the multiple elemental images and the metal-coated nanostructure yields patterned structural black color with a high pattern resolution (>12, 500 dpi). A virtual mask scheme is specially developed in the elemental image construction, allowing for eliminating the crosstalk between neighboring units and containing more information in one unit without the necessity for ultra-high-resolution fabrication process and sophisticated operation. The proposed QR code device, capable of being read by an unmodified smart phone, is inexpensive, mass-producible, nondestructive, unclonable and convenient for authentication. This new solution should take a place among the existing solutions to fight counterfeiting and QR code attacks.

As a key core component of cotton pickers, the spindle is prone to wear of the hook teeth. This research explores the wear characteristics of the spindle hook teeth of cotton pickers under different working areas. The sampled spindles were cut, the element composition and hardness of the spindle hook tooth coating and substrate were determined, the surface morphology of the spindle hook tooth was characterized, and its wear area and coating thickness were extracted. Results show that the main constituent elements of the coating and substrate are Cr and Fe, respectively, the hardness of the coating is about 1020 HV0.1, and the hardness of the substrate is 470~840 HV0.1. During the field operation, scratches appeared on the surface of the coating, the coating thickness layer gradually decreased, and the coating peeled off as the operating area increased. Afterward, scratches and oxidized particles appeared on the surface of the substrate, the wear rate accelerated, and the wear area gradually increased. The wear of the spindle hook teeth started to appear from the front and rear tooth tips up to the tooth edge, the back of the tooth, and the doffering edge, hence forming a long boot-shaped wear area.

In recent years, the moire imaging device has become one of the hot topics in the field of micro optics due to its strikingly visual three-dimensional (3D) effect which can be easily recognized by naked eye. Traditionally, the moire imaging film is composed of the superposition of a microlens array（MLA）and a micro pattern array (MPA）with high alignment accuracy. By the combination of the nanoimprinting and nanoprinting techniques, we fabricated a moire imaging film on a large-format substrate characterized by fluorescent enhancement effect under ultraviolet light illumination. By using a novel virtual mask technique, the MPA can contain more information than traditional one. It is worthy to note that the nanostructure is introduced to the MPA to promote the light efficiency of the fluorescent material. A synthetically magnified moire image with 3D effect is demonstrated. The moire imaging film has widely potential applications in 3D imaging, optical anti-counterfeiting, packaging, etc.

Modular Multilevel Converter (MMC) contains many Submodules (SM). Open-circuit fault of the switching devices which are connected in SM will result in the rise of the interphase circulating current, DC side voltage ripple, and other corresponding deteriorations. At present, many proposed methods which focus on the submodule inner switching fault are not quite easy to achieve in reality. Considering the previous studies, a more reliable and precise fault-location method requires to be introduced. In this paper, modal analysis is carried out first, then proposed a fault location method to solve the switching open-circuit fault. The method includes two components, one implements Fourier Decomposition on circulating current to locate the faulted phase, and then detects the instant value of capacitor voltage in the faulted phase as mentioned to locate the faulted SM. The efficiency of the fault location strategy is finally demonstrated in simulation and proved to be feasible.

BackgroundHuman meridian (Jingluo) system was hypothesized by traditional Chinese medicine (TCM) for thousands of years. In this hypothesis, there believed to be twelve formal meridian channels going through respective organs, carrying fluid and energy, and laying thermal effects. Some treatments based on meridians have been proved effective. However, existence of meridians has never been confirmed. The infrared photograph was employed to display the picture to the meridians since 1970. Unfortunately, no satisfactory results have been obtained. We think that only when a certain meridian is activated will there be thermal effect for successful infrared photograph.Methods We selected thirteen types of tea out of the herbs to activate the hypothesized twelve meridians for imagery taking. We collected 42 volunteers to drink teas and take infrared imageries in thirteen days. After every tea was drunk, infrared imageries of the human bodies were taken immediately. The highest temperatures of the fingers, palms, and above the organs were derived from the imageries. The averages and standard deviations of the standardized data of volunteers were calculated. Significances of the temperature difference among the body areas after drinking different teas were evaluated. ResultsWe found that the temperatures of the organs and fingers possibly connected by twelve hypothesized meridians rose together significantly, i.e., the thumbs and lung after white teas, index fingers and colon after blue teas, middle fingers and thymus after dark black teas, ring fingers and gallbladder after red black teas, little fingers and heart after yellow teas. The temperature distribution on the human bodies exhibited twelve patterns following the meridian hypothesis. Infrared imageries showed quite clear shapes of the organs activated by the teas, e.g., heart and kidneys by yellow teas, thymus by dark black teas, lungs and spleen by white teas, gallbladder and thyroid by red black teas, etc. Some high temperature lines also matched the hypothetic meridians. ConclusionsOur work displayed the imageries of the possible meridians for the first time, and proved with data that different foods may activate different organs following the meridian hypothesis, shedding light on a possible new method of targeted drug designs.

The synthesis and characterization of a new family of phosphine-oxide-supported aluminum formazanate complexes (7a, 7b, 8a, 9a) are reported. X-ray diffraction studies revealed that the aluminum atoms in the complexes adopt an octahedral geometry in the solid state. The equatorial positions are occupied by an N2O23‒ formazanate ligand, and the axial positions are occupied by L-type phosphine oxide donors. UV-vis absorption spectroscopy revealed that the complexes were strongly absorbing (ε ~ 30,000 M‒1 cm‒1) between 500 and 700 nm. The absorption maxima in this region were simulated using time-dependent density-functional theory. With the exception of 3-cyano substituted complex 7b, which showed maximum luminescence intensity in the presence of excess phosphine oxide, the title complexes are non-emissive in solution and the solid state. The electrochemical properties of the complexes were probed using cyclic voltammetry. Each complex underwent sequential one-electron oxidations in potential ranges of ‒0.12 to 0.29 V and 0.62 to 0.97 V, relative to the ferrocene/ferrocenium redox couple. Electrochemical reduction events were observed at potentials between ‒1.34 and ‒1.75 V. When combined with tri-n-propylamine as a coreactant, complex 7b acted as an electrochemiluminescence emitter with a maximum electrochemiluminescence intensity at a wavelength of 735 nm, red-shifted relative to the photoluminescence maximum of the same compound.

The synthesis and characterization of a new family of phosphine oxide supported aluminum formazanate complexes (7a,b, 8a, 9a) are reported. X-ray diffraction studies showed that the aluminum atoms in the complexes adopt an octahedral geometry in the solid state. The equatorial positions are occupied by an N