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In the digital microfluidic experiments, the improper adjustments of the camera focus and background illumination lead to the phenomena of low illumination and blurred edges in the droplet image, which seriously interferes with information acquisition. Removing these blurred factors is an essential pretreatment step before information extraction. In this paper, a generative adversarial network model combining multi-scale convolution and attention mechanism is proposed to reconstruct the droplet image. The feature reconstruction module in generator can reconstruct the image feature maps from multiple scales. The fusion module is used to fuse the multi-scale feature maps into a reconstructed sharp image. The new model was trained on the data set which was made by the Style Transfer. Experimental results show that the proposed model can significantly improve the visual quality of images, effectively reduce the blur and improve the background illumination.

This paper novel designed the local convergence configuration in the coaxial channels to study the two-phase flow (lubricating oil (continuous phase, flow rate Q c)/deionized water (dispersed phase, flow rate Q d)). Two geometric control variables, the relative position (x) and tapering characteristics (α), had the different effects on the droplet formation. The increase of relative position x caused the higher frequency and finer droplets, and the increase of convergence angle α, took the opposite effects. The results indicated that the equivalent dimensionless droplet length Ld/Wout and the flow rate ratio Qd/Qc had an exponential relationship of about 1/2. Similarly, it was found that the dispersed droplets generating frequency and the two-phase capillary number, CaTP = uTPμc/σ, had an exponential relationship. The advantage of the convergent configurations in micro-channel was the size and efficiency of droplet generation was very favorable to be controlled by α and x.

The geometries of micro-channel play a key role in forming of digital droplets, and can be real-time or effective controlling methodologies. Local convergence regions are designed in the rectangular cross-section channels on PMMA microchips, in which two-phase coaxial jets are introduced by inserting a syringe needle. The two-phase flow (lubricating oil (continuous phase, flow rate Q c)/deionized water (dispersed phase, flow rate Q d)) is considered. Two geometric control variables, the relative position (needle displacement x) and tapering characteristics (convergence angle α), are naturally adopted to discribe such geometry configurations. The micro-flow under the change of these two parameters is mainly studied in this paper. Four kinds of characteristic flow patterns, namely, sausages, slug, dripping and jetting, are found in the experiment, and their occurring parameters and developing dynamic characteristics are discussed. The experiment shows that the increase of inner needle displacement x can produce higher frequency and finer droplets, which is in consistent with our previous results obtained in round tube experiments and simulations. While increasing the convergence angle α, contrarily, takes opposite effects.

Layered two-dimensional (2D) materials such as MoS2 have attracted much attention for nano- and opto-electronics. Recently, intercalation (e.g. of ions, atoms, or molecules) has emerged as an effective technique to modulate material properties of such layered 2D films reversibly. We probe both the electrical and thermal properties of Li-intercalated bilayer MoS2 nanosheets by combining electrical measurements and Raman spectroscopy. We demonstrate reversible modulation of carrier density over more than two orders of magnitude (from 0.8 × 1012 to 1.5 × 1014 cm−2), and we simultaneously obtain the thermal boundary conductance between the bilayer and its supporting SiO2 substrate for an intercalated system for the first time. This thermal coupling can be reversibly modulated by nearly a factor of eight, from 14 ± 4.0 MW m−2 K−1 before intercalation to 1.8 ± 0.9 MW m−2 K−1 when the MoS2 is fully lithiated. These results reveal electrochemical intercalation as a reversible tool to modulate and control both electrical and thermal properties of 2D layers.

We report transport measurements on Josephson junctions consisting of Bi2Te3 topological insulator (TI) thin films contacted by superconducting Nb electrodes. For a device with junction length L = 134 nm, the critical supercurrent Ic can be modulated by an electrical gate which tunes the carrier type and density of the TI film. Ic can reach a minimum when the TI is near the charge neutrality regime with the Fermi energy lying close to the Dirac point of the surface state. In the p-type regime the Josephson current can be well described by a short ballistic junction model. In the n-type regime the junction is ballistic at 0.7 K < T < 3.8 K while for T < 0.7 K the diffusive bulk modes emerge and contribute a larger Ic than the ballistic model. We attribute the lack of diffusive bulk modes in the p-type regime to the formation of p-n junctions. Our work provides new clues for search of Majorana zero mode in TI-based superconducting devices., 6 pages, 4 figures, The manuscript with the same title will be published by Chinese Physics Letters

Acetylene hydrochlorination using Au/C as catalyst, is an important process to produce vinyl chloride. It is a highly exothermic and diffusion-controlled reaction with local hot spots and poor diffusion process in the fixed-bed reactor, weakening the catalytic performance of Au catalyst. The structuring of catalyst using solid SiC foam ceramic can solve the above problems through optimizing spatial distribution of Au/C, reducing the pressure drop and temperature rise. In order to further disperse Au/C, the novel SiC foam with hollow structure was manufactured to compare with solid SiC foam. The hollow foam structured catalyst has inside and outside surface, thinner catalyst coating and smaller Au particles. Thus it provides more active site accessible to the reactants and further shortens the diffusion distance, then improving the catalytic efficiency. The catalytic lifetime (acetylene conversion above 90%) of hollow SiC foam structured catalyst is 205 hours while that of solid foam is 126 hours at acetylene gaseous hourly space velocity (GHSV) of 120 h−1. In conclusion, the better dispersion of Au/C on hollow SiC foam supported structured catalyst is the main reason for activity and stability enhancement.

Microchannel reactors (MCR) have received considerable attention by researchers in recent years. A novel hollow-strut ceramic foam microchannel reactor (HSCF-MCR) taking the material and structural advantages of SiC foam was proposed. The reactor could be used as a structural scaffold for continuous gas or liquid phase flow and reaction because all of its struts are hollow and interconnected with each other. The three-dimensional (3-D) microstructure of the SiC foam was characterized by SEM and micro-CT method. Based on the tetrakaidecahedron cell model, computational fluid dynamics (CFD) method was utilized to analyze the single-phase flow characteristics and pressure drop of HSCF-MCR. The 3-D interconnected structure can form the static mixing effect of the flow fields inside the foam microchannel and strengthen the mass transfer process. Both channel diameter D and cell size L of the foam play a vital role in the pressure drop gradient δ of the fluid flowing through HSCF-MCR. When the ratio of D to L is controlled as 0.1, δ is minimized. The CFD simulation results contribute to the structural optimization and energy saving of HSCF-MCR for its applications in the future.

With the continuous development of smart grid technology, it is of great engineering application value and urgent practical demand to collect and manage more intelligently the operation and fault information of relay protection in 110kV and below substation. With the introduction of “cloud computing” technology, a cloud platform of fault information with good expansibility, high stability, loose coupling, strong reusability and convenient maintenance could be built up, which is the core of the system construction. In order to make full use of the existing data network channels and network resources in 110kV substation, a fault information system of relay protection, with its sub-station modeling and communication management, is presented based on “cloud computing” technology to realize a more efficient and convenient relay protection exchange between 110kV substation and the dispatching control center.

Modeling and prediction of electromagnetic wave absorbing properties of SiC foams as novel stealth materials in the X-band range of 8.2-12.4 GHz are presented. Appropriate material parameters, including the conductivity, volume fraction, cell size, thickness, and surface modified foam structure, are determined through optimization calculations, where the impedance difference between the SiC foam and free space is minimized. The minimum reflection coefficient, reaching -8 dB, is obtained when the SiC conductivity is about 2.27 S m(-1), the volume fraction is 28%, and the thickness is 20 mm in the case of SiC foam. For surface modified foam, the reflection can be less than -10 dB throughout the entire band investigated.

Controlling of water quality pollution and eutrophication of reservoirs has become a very important research topic in urban drinking water field. Xili reservoir is an important water source of drinking water in Shenzhen. And its water quality has played an important role to the city's drinking water security. A fifteen-month's field observation was conducted from April 2013 to June 2014 in Xili reservoir, in order to analyze the temporal and spatial distribution of water quality factors and seasonal variation of trophic states. Xili reservoir was seriously polluted by nitrogen. Judged by TN most of the samples were no better than grade VI. Other water quality factor including WT, SD, pH, DO, COD, TOC, TP, Fe, silicate, turbidity, chlorophyll-a were pretty good. One-way ANOVA showed that significant difference was found in water quality factors on month (p Latter rainy period > High temperature and rain free period > Temperature jump period > Winter drought period. Two-way ANOVA showed that months rather than locations were the key influencing factors of water quality factors succession.TLI (Σ) were about 35~52, suggesting Xili reservoir was in mycotrophic trophic states. As a result of runoff pollution, water quality at sampling sites 1 and 10 was poor. In the rainy season, near sampling sites 1 and 10, water appeared to be Light-eutrophic. The phytoplankton biomass of Xili reservoir was low. Water temperature was the main driving factor of phytoplankton succession.The 14 water quality factors were divided into five groups by factor analysis. The total interpretation rate was about 70.82%. F1 represents the climatic change represented by water temperature and organic pollution. F2 represents the concentration of nitrogen. F3 represents the phytoplankton biomass. F4 represents the sensory indexes of water body, such as turbidity, transparency.

In this paper, we consider the stimulated transition-radiation emission from a relativistic beam of electrons with short pulse, which passes through a plasma ripple and interacts with a plane wave. A set of self-consistent nonlinear equations is developed to describe the evolution of the radiation field in the plasma ripple. Analytic calculations of the small-signal gain and numerical computations of the nonlinear saturation of this emission are presented. It is shown that this device may provide a short-pulse coherent tunable source ranging from the microwave to the near-infrared regions, with a relatively high extraction efficiency.

Heterostructure based interface engineering has been proved an effective method for finding new superconducting systems and raising superconductivity transition temperature (TC). In previous work on one unit-cell (UC) thick FeSe films on SrTiO3 (STO) substrate, a superconducting-like energy gap as large as 20 meV, was revealed by in situ scanning tunneling microscopy/spectroscopy (STM/STS). Angle resolved photoemission spectroscopy (ARPES) further revealed a nearly isotropic gap of above 15 meV, which closes at a temperature of ~ 65 K. If this transition is indeed the superconducting transition, then the 1-UC FeSe represents the thinnest high TC superconductor discovered so far. However, up to date direct transport measurement of the 1-UC FeSe films has not been reported, mainly because growth of large scale 1-UC FeSe films is challenging and the 1-UC FeSe films are too thin to survive in atmosphere. In this work, we successfully prepared 1-UC FeSe films on insulating STO substrates with non-superconducting FeTe protection layers. By direct transport and magnetic measurements, we provide definitive evidence for high temperature superconductivity in the 1-UC FeSe films with an onset TC above 40 K and a extremely large critical current density JC ~ 1.7*106 A/cm2 at 2 K. Our work may pave the way to enhancing and tailoring superconductivity by interface engineering.

Diluted magnetic semiconductor (DMS) exhibits unique magnetic and transport properties. The well known DMS is (Ga,Mn)As that is in thin film form so far only. However Mn dopant brings both localized spins and carriers in Ga1−xMnxAs, result in the lack of independent control of local moment and carrier densities. It is therefore difficult to study or control charge and spin variable quantitatively. Here we report that an individual control of carrier and spin can be realized in a new type of DMS for Mn-doped I-II-V type semiconductor Li1+yZn1-xMnxAs in bulk. The Li(Zn,Mn)As polycrystalline samples showed ferromagnetic transition temperature (TC) up to 50K and spontaneous magnetization up to 2.9 μB per Mn. The other advantage of new DMS over III-V DMSs is the availability of bulk specimens so far for these type of DMS Moreover the new DMS shows a soft magnetic behavior with the coercive force < 100Oe which would be promising for prospective application. Muon spin relaxtion (μSR) probed static magnetic order of full volume in the ferromagnetic region. Electrical transport properties showed Li1+y(Zn,Mn)As (y = 0.05–0.1) compounds have p-type carriers since excess Li substitutes Zn sites presumably[1].