Databases of 2D material-substrate interfaces and 2D charged building blocks

Discovery of materials using“bottom-up”or“top-down”approach is of great interest in materials science.Layered materials consisting of two-dimensional(2D)building blocks provide a good platform to explore new materials in this respect.In van der Waals(vdW)layered materials,these building blocks are charge neutral and can be isolated from their bulk phase(top-down),but usually grow on substrate.In ionic layered materials,they are charged and usually cannot exist independently but can serve as motifs to construct new materials(bottom-up).In this paper,we introduce our recently constructed databases for 2D material-substrate interface(2DMSI),and 2D charged building blocks.For 2DMSI database,we systematically build a workflow to predict appropriate substrates and their geometries at substrates,and construct the 2DMSI database.For the 2D charged building block database,1208 entries from bulk material database are identified.Information of crystal structure,valence state,source,dimension and so on is provided for each entry with a json format.We also show its application in designing and searching for new functional layered materials.The 2DMSI database,building block database,and designed layered materials are available in Science Data Bank at https://doi.org/10.57760/sciencedb.j00113.00188.

Inversion of 3D density interface with PSO-BP method

BP( Back Propagation) neural network and PSO( Particle Swarm Optimization) are two main heuristic optimization methods,and are usually used as nonlinear inversion methods in geophysics. The authors applied BP neural network and BP neural network optimized with PSO into the inversion of 3D density interface respectively,and a comparison was drawn to demonstrate the inversion results. To start with,a synthetic density interface model was created and we used the proceeding inversion methods to test their effectiveness. And then two methods were applied into the inversion of the depth of Moho interface. According to the results,it is clear to find that the application effect of PSO-BP is better than that of BP network. The BP network structures used in both synthetic and field data are consistent in order to obtain preferable inversion results. The applications in synthetic and field tests demonstrate that PSO-BP is a fast and effective method in the inversion of 3D density interface and the optimization effect is evident compared with BP neural network merely,and thus,this method has practical value.

A 16 bit Stereo Audio ΣΔ A/D Converter

A 16 bit stereo audio novel stability fifth-order ∑△ A/D converter that consists of switched capacitor ∑△ modulators, a decimation filter, and a bandgap circuit is proposed. A method for the stabilization of a high order single stage ∑△ modulator is also proposed. A new multistage comb filter is used for the front end decimation filter. The ∑△ A/D converter achieves a peak SNR of 96dB and a dynamic range of 96dB. The ADC was implemented in 0. 5μm 5V CMOS technology. The chip die area occupies only 4. 1mm × 2.4mm and dissipates 90mW.

3D Artificial Array Interface Engineering Enabling Dendrite-Free Stable Zn Metal Anode

The ripple effect induced by uncontrollable Zn deposition is considered as the Achilles heel for developing high-performance aqueous Zn-ion batteries.For this problem,this work reports a design concept of 3D artificial array interface engineering to achieve volume stress elimination,preferred orientation growth and dendrite-free stable Zn metal anode.The mechanism of MXene array interface on modulating the growth kinetics and deposition behavior of Zn atoms were firstly disclosed on the multi-scale level,including the in-situ optical microscopy and transient simulation at the mesoscopic scale,in-situ Raman spectroscopy and in-situ X-ray diffraction at the microscopic scale,as well as density functional theory calculation at the atomic scale.As indicated by the electrochemical performance tests,such engineered electrode exhibits the comprehensive enhancements not only in the resistance of corrosion and hydrogen evolution,but also the rate capability and cyclic stability.High-rate performance(20 mA cm^(-2))and durable cycle lifespan(1350 h at 0.5 mA cm^(-2),1500 h at 1 mA cm^(-2)and 800 h at 5 mA cm^(-2))can be realized.Moreover,the improvement of rate capability(214.1 mAh g^(-1)obtained at 10 A g^(-1))and cyclic stability also can be demonstrated in the case of 3D MXene array@Zn/VO2battery.Beyond the previous 2D closed interface engineering,this research offers a unique 3D open array interface engineering to stabilize Zn metal anode,the controllable Zn deposition mechanism revealed is also expected to deepen the fundamental of rechargeable batteries including but not limited to aqueous Zn metal batteries.

Seismic traveltime inversion of 3D velocity model with triangulated interfaces

Seismic traveltime tomographic inversion has played an important role in detecting the internal structure of the solid earth. We use a set of blocks to approximate geologically complex media that cannot be well described by layered models or cells. The geological body is described as an aggregate of arbitrarily shaped blocks,which are separated by triangulated interfaces. We can describe the media as homogenous or heterogeneous in each block. We define the velocities at the given rectangle grid points for each block,and the heterogeneous velocities in each block can be calculated by a linear interpolation algorithm. The parameters of the velocity grid positions are independent of the model parameterization,which is advantageous in the joint inversion of the velocities and the node depths of an interface. We implement a segmentally iterative ray tracer to calculate traveltimes in the 3D heterogeneous block models.The damped least squares method is employed in seismic traveltime inversion,which includes the partial derivatives of traveltime with respect to the depths of nodes in the triangulated interfaces and velocities defined in rectangular grids. The numerical tests indicate that the node depths of a triangulated interface and homogeneous velocity distributions can be well inverted in a stratified model.

3-D structural reconstruction of Moho in the Tangshan earthquake area by using inversion of curved interface

A method for inverting 3 D curved interface and layer velocity by using travel time of reflected waves is studied. Each interface is described with sectional, incomplete cubic polynomial. A fast 3 D ray tracing method is used in forward problem, and a least squares method with variable damping is adopted in the inverse problem. Result from numerical modelling shows that the solution can converge fast on the true model. Observational data from the Tangshan earthquake area are processed, 3 D Moho discontinuity in the area is rebuilt, and finally, the relationship between the regional structure and seismicity is revealed.

Two-step interface and velocity inversion—— Study o e of the Tangshan seismic region

This paper studies the computation method of two step inversion of interface and velocity in a region. The 3 D interface is described by a segmented incomplete polynomial; while the reconstruction of 3 D velocity is accomplished by the principle of least squares in functional space. The computation is carried out in two steps. The first step is to inverse the shape of 3 D interface; while the second step is to do 3 D velocity inversion by distributing the remaining residual errors of travel time in accordance with their weights. The data of seismic sounding in the Tangshan Luanxian seismic region are processed, from which the 3 D structural form in depth of the Tangshan seismic region and the 3 D velocity distribution in the crust below the Tangshan Luanxian seismic region are obtained. The result shows that the deep 3 D structure in the Tangshan seismic region trends NE on the whole and the structure sandwiched between the NE trending Fengtai Yejituo fault and the NE trending Tangshan fault is an uplifted zone of the Moho. In the 3 D velocity structure of middle lower crust below that region, there is an obvious belt of low velocity anomaly to exist along the NE trending Tangshan fault, the position of which tallies with that of the Tangshan seismicity belt. The larger block of low velocity anomaly near Shaheyi corresponds to a denser earthquake distribution. In that region, there is an NW trending belt of high velocity anomaly, probably a buried fault zone. The lower crust below the epicentral region of the Tangshan M S=7.8 earthquake is a place where the NE trending belt of low velocity anomaly meets the NW trending belt of high velocity anomaly. The two sets of structures had played an important role in controlling the preparation and occurrence of the M S=7.8 Tangshan earthquake.

Implementation and verification of interface constitutive model in FLAC^(3D)

Due to the complexity of soil-structure interaction, simple constitutive models typically used for interface elements in general computer programs cannot satisfy the requirements of discontinuous deformation analysis of structures that contain different interfaces. In order to simulate the strain-softening characteristics of interfaces, a nonlinear strain-softening interface constitutive model was incorporated into fast Lagrange analysis of continua in three dimensions （FLAC3D） through a user-defined program in the FISH environment. A numerical simulation of a direct shear test for geosynthetic interfaces was conducted to verify that the interface model was implemented correctly. Results of the numerical tests show good agreement with the results obtained from theoretical calculations, indicating that the model incorporated into FLAC3D can simulate the nonlinear strain-softening behavior of interfaces involving geosynthetic materials. The results confirmed the validity and reliability of the improved interface model. The procedure and method of implementing an interface constitutive model into a commercial computer program also provide a reference for implementation of a new interface constitutive model in FLAC3D.

TEXTURES, INTERFACE AND FRACTURE OF A 1D-C/C PREPARED BY CVD

A unidirectional carbon/carbon composite (1D-C/C) of low bulk density with textures of poruns granular and isotropic carbons sharply manifests brittle fracture and does not display high pseudoplasticity as expected. The results of transmisson electron microscopy (TEM) studies show that the strong interface of fiber-matrix should determine its fracture mode.

Microstructure and properties of composites gun drill bit/drill pipe interface produced by 3D printing method

In this paper,the rapid and integrated manufacture method of 3 D printing gun drill is put forward.The 3 D printing process test of the composites gun drill composed of medium carbon steel drill shank,low alloy steel drill pipe and tungsten cobalt hard alloy drill bit is conducted.Microstructure and morphology of the composites gun drill interface between low alloy steel and tungsten cobalt hard alloy is analyzed using SEM.Element distribution and Phase composition of the interface between low alloy steel and tungsten cobalt hard alloy were tested and analyzed by EDS and XRD respectively.The oxidation resistance,micro hardness and corrosion resistance of the interface between low alloy steel and tungsten cobalt hard alloy were analyzed.The results show that the interface performance of 3 D printing composite gun drill is better than that of the welding gun drill.The rapid and integrated 3 D printing method is feasible for gun drill manufacture.

The Design of A/D Converter Circuit Adopting the Technology of PWM

This text has expounded the working principle of realizing A/D conversion that utilizes the timer within MCU and combinesthe technology of PWM. The design of hardware circuit, improved gradual approached trial arithmetic and relevant program design arediscussed in detail. And it has analyzed the resolution of A/D converter based on the technology of PWM, etc.

Effect of Interface Nanotexture on Light Extraction of InGaN-Based Green Light Emitting Diodes

We report the enhancement of the light extraction of InGaN-based green light emitting diodes （LEDs） via the interface nanotexturing. The texture consists of high-density nanocraters on the surface of a sapphire substrate with an in situ etching. The width of nanocraters is about 0.5 μm and the depth is around 0.1 μm. It is demonstrated that the LEDs with interface texture exhibit about a 27% improvement in luminance intensity, compared with standard LEDs. High power InGaN-based green LEDs are obtained by using the interface nanotexture. An optical ray-tracing simulation is performed to investigate the effect of interface nanotexture on light extraction.

Reverse Droop Control-based Smooth Transfer Strategy for Interface Converters in Hybrid AC/DC Distribution Networks

Hybrid AC/DC distribution networks are promising candidates for future applications due to their rapid advancement in power electronics technology.They use interface converters(IFCs)to link DC and AC distribution networks.However,the networks possess drawbacks with AC voltage and frequency offsets when transferring from grid-tied to islanding modes.To address these problems,this paper proposes a simple but effective strategy based on the reverse droop method.Initially,the power balance equation of the distribution system is derived,which reveals that the cause of voltage and frequency offsets is the mismatch between the IFC output power and the rated load power.Then,the reverse droop control is introduced into the IFC controller.By using a voltage-active power/frequency-reactive power(U-P/f-Q)reverse droop loop,the IFC output power enables adaptive tracking of the rated load power.Therefore,the AC voltage offset and frequency offset are suppressed during the transfer process of operational modes.In addition,the universal parameter design method is discussed based on the stability limitations of the control system and the voltage quality requirements of AC critical loads.Finally,simulation and experimental results clearly validate the proposed control strategy and parameter design method.

An Overview of Bidirectional DC-DC Converter Topologies and Control Strategies for Interfacing Energy Storage Systems in Microgrids

A microgrid is defined as a local electric power distribution system with diverse DG （distributed generation） units, energy storage systems, and loads, which can operate as a part of the distribution system or when needed can operate in an islanded mode. Energy storage systems play a key role in improving security, stability, and power quality of the microgrid. During grid-connected mode, these storage units are charged from various DG sources as well as the main grid. During islanded mode, DG sources along with the storage units need to supply the load. Power electronic interfaces between the microgrid buses and the storage units should be able to detect the mode of operation, allow seamless transition between the modes, and allow power flow in both directions, while maintaining stability and power quality. An overview of bidirectional converter topologies relevant to microgrid energy storage application and their control strategies will be presented in this paper.

A 12bit 300MHz Current-Steering CMOS D/A Converter

The proposed DAC consists of a unit current-cell matrix for 8MSBs and a binary-weighted array for 4LSBs,trading-off between the precision,speed,and size of the chip.In order to ensure the linearity of the DAC,a double Centro symmetric current matrix is designed by the Q2 random walk strategy.To achieve better dynamic performance,a latch is added in front of the current switch to change the input signal,such as its optimal cross-point and voltage level.For a 12bit resolution,the converter reaches an update rate of 300MHz.

A flexible three-dimensional electrode mesh:An enabling technology for wireless brain-computer interface prostheses

The neural interface is a key component in wireless brain–computer prostheses.In this study,we demonstrate that a unique three-dimensional(3D)microneedle electrode on a flexible mesh substrate,which can be fabricated without complicated micromachining techniques,is conformal to the tissues with minimal invasiveness.Furthermore,we demonstrate that it can be applied to different functional layers in the nervous system without length limitation.The microneedle electrode is fabricated using drawing lithography technology from biocompatible materials.In this approach,the profile of a 3D microneedle electrode array is determined by the design of a two-dimensional(2D)pattern on the mask,which can be used to access different functional layers in different locations of the brain.Due to the sufficient stiffness of the electrode and the excellent flexibility of the mesh substrate,the electrode can penetrate into the tissue with its bottom layer fully conformal to the curved brain surface.Then,the exposed contact at the end of the microneedle electrode can successfully acquire neural signals from the brain.

A simplified method for the determination of vertically loaded pile-soil interface parameters in layered soil based on FLAC3D

The numerical analysis of pile-soil interaction commonly requires a lot of trial works to determine the interface parameters and the accuracy cannot be ensured normally. Considering this, this paper first conducts a sensitivity analysis to figure out the influence of interface parameters on the bearing behavior of a single pile in sand. Then, a simplified method for the determination of pile-soil interface parameters in layered soil is proposed based on the parameter studies. Finally, a filed loading test is used for the validation of the simplified method, and the calculated results agree well with the monitoring data. In general, the simplified method proposed in this paper works with higher accuracy and consumes less time compared with the traditional trial works, especially on the determinations ofinterfacial cohesive and interracial friction angle.

A titanium dioxide nanorod array as a high-affinity nano-bio interface of a microfluidic device for efficient capture of circulating tumor cells

Nanomaterials show promising opportunities to address clinical problems （such as insufficient capture of circulating tumor cells; CTCs） via the high surface area-to-volume ratio and high affinity for biological cells. However, how to apply these nanomaterials as a nano-bio interface in a microfluidic device for efficient CTC capture with high specificity remains a challenge. In the present work, we first found that a titanium dioxide （TiO2） nanorod array that can be conveniently prepared on multiple kinds of substrates has high affinity for tumor cells. Then, the TiO2 nanorod array was vertically grown on the surface of a microchannel with hexagonally patterned Si micropillars via a hydrothermal reaction, forming a new kind of a micro-nano 3D hierarchically structured microfluidic device. The vertically grown TiO2 nanorod array was used as a sensitive nano-bio interface of this 3D hierarchically structured microfluidic device, which showed high efficiency of CTC capture （76.7% ± 7.1%） in an artificial whole-blood sample.

FLAC3D复杂模型interface建模方法探讨

针对FLAC3D中复杂模型接触单元(interface)建模难的问题,利用ansys强大的前处理功能,探讨了适用于岩土工程全过程数值模拟分析的复杂模型"先实体面后接触面"的interface建模方法。并将该方法运用到实际的工程数值计算过程中,验证了该建模方法的有效性、实用性,对今后的FLAC3D的接触面的建模过程具有重要的参考价值。

FLAC^(3D)模型interface法向应力的MATLAB处理

采矿工程领域经常用到FLAC3D软件进行工作面开挖、巷道支护以及边坡稳定性的研究,但FLAC3D在后处理有关力时仅能出云图。针对FLAC3D在后处理功能中的缺陷,利用MATLAB在数据可视化方面的优越性,通过用FLAC3D自带的fish语言提取相应结构的应力,特别是interface上的法向应力,并运用MATLAB将提取的应力用三维网格展现出来,可以为FLAC3D后续分析提供重要价值。