COMPACTLY SUPPORTED NON-TENSOR PRODUCT FORM TWO-DIMENSION WAVELET FINITE ELEMENT

Some theorems of compactly supported non-tensor product form two-dimension Daubechies wavelet were analysed carefully. Compactly supported non-tensor product form two-dimension wavelet was constructed, then non-tensor product form two dimension wavelet finite element was used to solve the deflection problem of elastic thin plate. The error order was researched. A numerical example was given at last.

Two-Dimensional Euler Adaptive Mesh Method on Detonation

The adaptive mesh refinement （AMR） method is applied in the 2-D Euler multi-component elasticplastic hydrodynamics code （MEPH2Y）. It is applied on detonation. Firstly, the AMR method is described, including a conservative spatial interpolation, the time integration methodology with the adapitve time increment and an adaptive computational region method. The advantage of AMR technique is exhibited by numerical examples, including the 1-D C-J detonation and the 2-D implosion ignited from a single point. Results show that AMR can promote the computational efficiency, keeping the accuracy in interesting regions.

EFFECT OF SUSPENDED SOLID PARTICLES ON UNSTABILITY OF TWO-DIMENSION MIXING LAYER

By considering the effect of suspended solid particles in the ordinary equations for two-dimension inviscid incompressible mixing layer, the Rayleigh equation and the modified Rayleigh equation are obtained. And then, by solving the corresponding eigen-value equations with numerical computational method, the relation curves between perturbation frequency and spacial growth rate of the mixing layer for the varying particle loading, ratio of particle velocity to fluid velocity and Stokes number are got. Sever al important conclusions on the effect of suspended solid particles on unstability of the mixing layer are presented in the end by analyzing all the relation curves.

Surface Topography of Fine-grained ZrO_2 Ceramic by Two-dimensional Ultrasonic Vibration Grinding

The surface quality of fine-grained ZrO2 engineering ceramic were researched using 270# diamond wheel both with and without work-piece two-dimension ultrasonic vibration grinding（WTDUVG）. By AFM images, the surface topography and the micro structure of the two-dimensional ultrasonic vibration grinding ceramics were especially analyzed. The experimental results indicate that the surface roughness is related to grinding vibration mode and the material removal mechanism. Surface quality of WTDUVG is superior to that of conventional grinding, and it is easy for two-dimensional ultrasonic vibration grinding that material removal mechanism is ductile mode grinding.

The Current Situation and the Development Trend of Two-dimensional Clothing in China

As a kind of subculture, The two-dimensional culture came of age during the 1970s in Japan and spread to China in the 1980s. In China, the culture has become an important economic force and social capital get more and more attention to it as well. This paper mainly discusses the origin and development of the two-dimensional clothing, and summed up the inherent characteristics and the internal developing law of it, furthermore, on the stage of current situation of two-dimensional economy this paper will conclude the development trend of next days.

Structure Determination of By-product in Grignard Reaction for Preparing Mifepristone Derivatives

Aim To determine the structure of the by-product produced in Grignard reaction for preparing mifepristone derivatives, and elucidate the reaction mechanism.Methods The structure of the by-product was determined with elemental analysis, one- and two-dimension spectra NMR (DEPT, 1H-1Hcosy, HMQC, HMBC) and compared with those of mifepristone.Results The main by-product was 11,17-di-addition product of Grignard reagent of N, N-dimethylamino phenyl bromide.Conclusion This is the first complete assignment of 1H NMR and 13C NMR of compound (3).

CFD Simulation of Film Flow and Gas/Liquid Countercurrent Flow on Structured Packing

A mathematic model of two-phase flow and a physical model of two-dimensional (2D) vertical section for the plate-type structured packing Mellapak 250.Y were set up and verified. The models were used to study the influence of packing’s surface microstructure on the continuity of liquid film and the amount of liquid holdup. Simulation results show that the round corner shape and micro wavy structure are favorable in remaining the continuity of liquid film and increasing the amount of liquid holdup. The appropriate liquid flow rate was determined by investigating different liquid loadings to obtain an unbroken liquid film on the packing surface. The pressure difference between inlet and outlet for gas phase allowed gas and liquid to flow countercurrently in a 2D computational domain. The direction change of gas flow occurred near the phase interface area.

Advances and Challenges in Two‑Dimensional Organic–Inorganic Hybrid Perovskites Toward High‑Performance Light‑Emitting Diodes

Two-dimensional(2D)perovskites are known as one of the most promising luminescent materials due to their structural diversity and outstanding optoelectronic properties.Compared with 3D perovskites,2D perovskites have natural quantum well structures,large exciton binding energy(Eb)and outstanding thermal stability,which shows great potential in the next-generation displays and solidstate lighting.In this review,the fundamental structure,photophysical and electrical properties of 2D perovskite films were illustrated systematically.Based on the advantages of 2D perovskites,such as special energy funnel process,ultrafast energy transfer,dense film and low efficiency roll-off,the remarkable achievements of 2D perovskite light-emitting diodes(PeLEDs)are summarized,and exciting challenges of 2D perovskite are also discussed.An outlook on further improving the efficiency of pure-blue PeLEDs,enhancing the operational stability of PeLEDs and reducing the toxicity to push this field forward was also provided.This review provides an overview of the recent developments of 2D perovskite materials and LED applications,and outlining challenges for achieving the high-performance devices.

Frequency modulated weak signal detection based on stochastic resonance and genetic algorithm

Stochastic resonance system is subject to the restriction of small frequency parameter in weak signal detection,in order to solve this problem,a frequency modulated weak signal detection method based on stochastic resonance and genetic algorithm is presented in this paper. The frequency limit of stochastic resonance is eliminated by introducing carrier signal,which is multiplied with the measured signal to be injected in the stochastic resonance system,meanwhile,using genetic algorithm to optimize the carrier signal frequency,which determine the generated difference-frequency signal in the lowfrequency range,so as to achieve the stochastic resonance weak signal detection. Results showthat the proposed method is feasible and effective,which can significantly improve the output SNR of stochastic resonance,in addition,the system has the better self-adaptability,according to the operation result and output phenomenon,the unknown frequency of the signal to be measured can be obtained,so as to realize the weak signal detection of arbitrary frequency.

Analysis and evaluation on seepage stability of Hongxing reservoir dam,Heilongjiang

Hongxing reservoir was constructed on the floodplain of Hulan River in Heilongjiang. The geological problem of the reservoir is the seepage of the dam base and its related seepage stability. The leakage of the reservoir is caused by the water head differences between the upstream and downstream of the dam. Severe seepage could decrease the engineering benefits of the reservoir. Moreover,infiltration function of water will influence the safety of the dam. Through the analysis on the granule constitute and the formation of the dam base,the types of the seepage failure apt to happen were defined and the anti-infiltration and the permissible depression ratio were determined. Using the numerical simulation software GMS,the two-dimension numerical modeling has been carried out to analyze the seepage field of the reservoir. Through the two conditions modeling with concrete impervious wall and no concrete impervious wall,the largest flow rate,single-wide seepage discharge and the max infiltration gradient of the dam base were calculated. According to the permeable depression ratio of the dam base,the seepage stability of Hongxing reservoir dam base was analyzed.

A 2D NiFe Bimetallic Metal–Organic Frameworks for Efficient Oxygen Evolution Electrocatalysis

The oxygen evolution reaction(OER) is the cornerstone for many important energy conversion devices, including metal–air battery and water splitting.Herein, an optimized NiFe-based metal–organic framework is developed as highly efficient active material for OER. It just needs a low overpotential of 0.31 V to deliver a current density of 10 mA cm-2 with a favorable Tafel slope of 43.7 mV dec-1 in 0.1 M KOH electrolyte for the as-prepared Ni0.75Fe0.25 BDC, which is superior to RuO2. This efficient catalytic performance is due to the introduction of Fe in Ni-based MOFs could benefit the kinetics and charge transfer efficiency, resulting in the optimal activity toward OER. Besides, the obtained active material demonstrates good stability, suggesting the great potential value in sustainable electrochemical energy storage and conversion devices.

In situ revealing the reconstruction behavior of monolayer rocksalt CoO nanosheet as water oxidation catalyst

The reconstruction during oxygen evolution reaction (OER) significantly affects the electronic and local geometry structure of metal sites in electrocatalyst.Compared with well-investigated cobalt-based materials,the reconstruction of rocksalt CoO with purely Co^(2+) in octahedral (Oh) coordination has not been revealed in detail.Herein,monolayer Co O supported on reduced graphene oxide (r GO) was synthesized via a one-pot hydrothermal strategy with calcinating in Ar atmosphere.The structure evolution of twodimension (2D) Co O/r GO during OER was revealed by in situ X-ray absorption spectroscopy (XAS).The transition from Co O toward Co3O_(4) already occurred at open circuit potential,further enhanced at 1.23 V (vs.RHE).The Co Ox(OH)ywas determined as the active phase at 1.53 V,displaying a tetrahedral Co coordination defective spinel Co_(3)O_(4) with the Co-O shell that featured the (oxy)hydroxide,not the standard Co OOH.After OER,the irreversible transition from CoO to Co_(3)O_(4) was observed.In contrast,in situ Raman spectra revealed a reversible amorphization process on Co_(3)O_(4)/r GO under operation conditions.Furthermore,this study indicated that the reconstruction behavior could be more effectively revealed by XAS using 2D materials.

A NEW APPROACH TO MANUFACTURING 3D WOVEN PREFORMS USED FOR STRUCTURAL COMPOSITES

The manufacturing of three-dimensional textile preforms used for composites started to re-ceive much attention in the last decade.The major barriers to accelerating the transition from thelamination of two-dimensional fabrics to manufacturing integral three-dimensional near-netshaped textile preforms are high cost and database deficiency.To reduce the cost of weaving three-dimensional preforms,and make full use of the potential of conventional looms,a rig was designedwhich can convert two-dimensional woven fabric to particular three-dimensional preforms wherethe yarn is orientated in the directions of maximum stress.

Measuring Structural Parameters of Knitted Fabrics by Digital Image Processing Techniques

In the knitting industry the measurements of the stitch density and the stitch length are usually done manually, which may lead to lower efficiency and less definition and also bring subjective ideas into the test results. In order to improve the effect we can measure with Digital Image Processing Techniques. A piece of sample is scanned into computer and changed into a digital image, which is processed with media filtering. To acquire the power spectrum, the image in the spatial domain is converted into the frequency domain. Picking up the characteristic points describing the stitch density and the stitch length separately in the power spectra and reconstructing them, the values of the stitch density and the stitch length could be calculated. When measuring the stitch length, we should establish a geometric model of the stitch based en the digital image processing, which provides a method to transform the stitch length in the two-dimensien space into the three-dimensien space and to measure the value of the stitch length more accurately. This method also provides a new way to measure the stitch length without damaging the fabric.

A New Method for Measuring the Stitch Length of Weft Knitted Fabric in a Static Environment

It is essential to measure the stitch length of weft knitted fabric in a static environment for economy and improving productivity. The image inputted was dealt with the digital image processing techniques： the paper carried out the transformation of grey scale; then removed impurities with filtering; the characteristic of the stitch structure was abstracted by using the Fourier transform technique. To obtain the stitch length more accurately, we should establish ageometric medal of the stitch lined on the digital image processing, which provides a way to transform the stitch length in the two-dimenslon space into a three-dimension space. This study provides a new methed for measuring the stitch length without damaging the fabric.

Monolayer single crystal two-dimensional quantum dots via ultrathin cutting and exfoliating

Two-dimensional(2D)atomically thin quantum dots(QDs)possess extraordinary electrical and optical properties.However,fabricating high quality 2D QDs via a universal and reliable technique remains a challenge.Here,we report a simple strategy to prepare high quality,monolayer single crystal 2D QDs via ultrathin cutting 2D bulk single crystals by ultramicrotome,followed by an exfoliation process.The as-prepared 2D QDs have pristine surface,high quality,high monolayer yield and high photoluminescence quantum yield(the highest photoluminescence quantum yield of WS2 is18%),which can be used as promising,low toxic,biocompatible,and good cell-permeability fluorescent labeling agents for in vitro imaging.

Shape/size controlling syntheses, properties and applications of two-dimensional noble metal nanocrystals

Two dimensional （2D） nanocrystals of noble metals （e.g., Au, Ag, Pt） often have unique structural and environmental properties which make them useful for applications in electronics, optics, sensors and biomedi- cines. In recent years, there has been a focus on discovering the fundamental mechanisms which govern the synthesis of the diverse geometries of these 2D metal nanocrystals （e.g., shapes, thickness, and lateral sizes）. This has resulted in being able to better control the properties of these 2D structures for specific applications. In this review, a brief historical survey of the intrinsic anisotropic properties and quantum size effects of 2D noble metal nanocrystals is given and then a summary of synthetic approaches to control their shapes and sizes is presented. The unique properties and fascinating applica- tions of these nanocrystals are also discussed.

Electrical contacts to two-dimensional transition-metal dichalcogenides

Two-dimensional(2D) transition-metal dichalcogenides(TMDCs) have attracted enormous interests as the novel channel materials for atomically thin transistors. Despite considerable progress in recent years, the transistor performance is largely limited by the excessive contact resistance at the source/drain interface. In this review, a summary of recent progress on improving electrical contact to TMDC transistors is presented. Several important strategies including topology of contacts, choice of metals and interface engineering are discussed.

Ab initio electronic transport study of two-dimensional silicon carbide-based p–n junctions

Two-dimensional silicon carbide（2d-SiC） is a viable material for next generation electronics due to its moderate,direct bandgap with huge potential.In particular,its potential for p–n junctions is yet to be explored.In this paper,three types of 2d-SiC-based p–n junctions with different doping configuration are modeled.The doping configurations refer to partially replacing carbon with boron or nitrogen atoms along the zigzag or armchair direction,respectively.By employing density functional theory,we calculate the transport properties of the SiC based p–n junctions and obtain negative differential resistance and high rectification ratio.We also find that the junction along the zigzag direction with lower doping density exhibits optimized rectification performance.Our study suggests that 2d-SiC is a promising candidate as a material platform for future nano-devices.