Commutation failure, which is a very frequent dynamic event in HVDC inverters, can deteriorate the availability of links and thus affect performance power system. Most commutation failures are caused by voltage reduction due to ac system faults. In this paper, efforts made lower effect failure on system, remedy implemented fuzzy controller. order achieve control flexibility, output controller appropriate setting self-adjusting proportional factor. The validity effectiveness verified...

The 0.72 Bi ( Fe 1− x Al ) O 3 –0.28 BaTiO = 0, 0.01, 0.03, 0.05, and 0.07, abbreviated as BFA – BT lead‐free high‐temperature ceramics were prepared by the conventional ceramic processing. Systematic investigation on microstructures, crystalline structures, dielectric piezoelectric properties, stability of properties was carried out. structures evolve from rhombohedral structure with < 0.01 to coexistence pseudocubic phases ≈ finally when > 0.03. Remarkably near‐zero temperature...

1D fibers of Bombyx mori silk fibroin (SF) and poly(l-lactide) (SF-s-PLLA) with side-by-side parallel arrangement the two components in a single fiber made by electrospinning are presented. The both randomly oriented aligned two-in-one was confirmed scanning electron confocal laser microscope studies. molecular orientation secondary structure SF PLLA were dependent on alignment annealing conditions. sides retained their individual before after without affecting each other significant way....

In bioanalysis, precisely isolating liquid reactions in distinct systems or at different temporal sequences is vital for ensuring accurate results devoid of crosstalk. However, passive isolation unattainable through existing microfluidic valves. Here, bridge cutting valves (LBCVs) are introduced to automatically segregate liquids by establishing airlocks, offering an innovative structure distribution. The principle breakup studied and applied the design LBCVs. Additionally, monolithic chips...

To solve the problem of false defect detection owing to interference texture attribute ceramic tiles, a method for detecting surface defects in complex-textured tiles is proposed. Based on visual principle tile surfaces, an image acquisition system established obtain image. After segmentation and correction, are preliminarily detected using saliency method. Then, sub-block containing area cut out secondary detection. The eliminated, final completed determination feasibility effectiveness...

Abstract Nature is an intriguing inspiration for designing a myriad of functional materials. However, artificial mimicking bioinspired structures usually requires different specialized procedures and setups. In this study, new upscalable concept presented that allows to produce two bioinspired, bicomponent fiber morphologies (side‐by‐side coaxial bead‐on‐string) using the same electrospinning setup, just by changing employed spinning solvent. The generated are highly attractive...

To understand the effect of coupling parameters between two ultrasonic waves on acoustic cavitation, in this work, Keller-Miksis equation was introduced to built a bubble dynamics model that used describe dynamic evolution and discuss dual-frequency parameters, such as frequency difference f (5 ∼ 280 kHz), phase φ (0 7π/4 rad), power allocation ratio β 9), cavitation presence irradiation. The enhancement attenuation have also been analyzed detail by comparing different combinations with...

The integrable coupling is one of the most important topics in nonlinear physics. This paper creates a novel KP and solves it via recently-developed dark parameterization procedure.

A tubular highly porous scaffold of polylactide (PLA) and poly-ε-caprolactone (PCL) is fabricated by self-rolling a 2D fibrous bilayer PLA PCL in water without use any classical thermo-/pH-responsive polymers. The diameter the tube are dependent upon thickness temperature. 75 µm thick (PLA = 25 µm; 50 µm) rolls to hollow around 0.41 mm with multilayered wall at 40 °C within 5 min. tubes keep their form size all temperatures once they formed. interesting properties tubes, that is, permeation...

Concrete is the most widely used construction material, and carbon nano-fiber (CNF) has many advantages in both mechanical electrical properties such as high strength, Young's modulus conductivity. These characteristics enable nanofibers to bridge microcracks inside concrete absorb energy normally released during crack propagation. Due large Van der Waals forces between nano-fibers, however, uniform dispersion of throughout cement matrix difficult achieve. In order improve dispersal CNF,...

Abstract Ultrasound mediated facile ligand exchange method in suspension for the formation of polystyrene‒grafted silver nanoparticles is reported. Amazingly, this allows even grafting very high molecular weight polystyrenes (up to 217 200 g mol −1 ) having a single terminal thiol group at chain end. Detailed studies are carried out gain insights role ligands and mechanism reactions. Key factors determined be droplet by ultrasonification low content, which enhances availability end...

区域性地震滑坡信息获取目前主要通过遥感目视解译和计算机提取,存在主观性强、耗时费力、提取精度低等问题,导致难以满足灾后应急调查、灾情评估等方面的应用需求。采用资源三号、高分一号高分辨率遥感影像,以汶川震区为实验区,在地震滑坡灾害特征分析的基础上,通过多尺度最优分割方法构建多层次滑坡对象,融合光谱、纹理、几何等影像特征和地形特征信息建立多维滑坡识别规则集合,基于高分辨率影像认知模式与场景理解过程提出滑坡分层识别模型,从而实现地震滑坡空间分布及其滑源区、滑移区和堆积区的准确识别。实验区分析结果显示最低识别精度为81.89%,而滑坡的堆积区最容易被分辨,识别方法具有可推广性。研究成果可为灾后应急调查提供技术支撑,并促进国产高分辨率遥感卫星的地质灾害应用。

VSC-based HVDC is more and concerned recently to improve power system stability due controllability of its IGBT valve. In this paper, a two-machine model with transmission established analyzed. Through eigenvalue analysis, it shown that the enhanced significantly proposed in systems. Furthermore, digital simulation studies are conducted using well-established PSCAD/ EMTDC software package show effectiveness damping oscillations when faults occurred

Machine vision image quality is significantly affected by illumination. Uniform illumination of a rectangular target surface requires function for evaluating the system. In this study, based on an LED array light source illuminance model, such evaluation was established. Further, influence source's structure analyzed using single-factor analysis method to determine boundary conditions, and it then solved genetic algorithm finalize structural design. An experimental platform built measure...

Nowadays, the most widely used variable speed wind turbine type for unites above 1MW is doubly fed induction generator (DFIG). Because of relative small rating power converters, turbines based on DFIG are very sensitive to grid disturbances, especially voltage dips during faults. In this paper, two control strategies stator flux, including a synchronous approach with an open-loop flux and asynchronous closed-loop control, proposed compared in order show their influence dynamic behavior...

Aiming at the difficulty of detecting surface defects complex texture tiles, a salient target detection method based on human visual attention mechanism is proposed and used for tile defects. Firstly, image ceramic pretreated using single-scale SSR light correction bilateral filtering method; Secondly, according to principle contrast high-frequency suppression in mechanism, aiming "imaging" "aggregation" characteristics background textures, model established determine mark defects.According...

The problem of the combined control system combining natural light and artificial is how to use maximally maintain regulated illumination office building at same time. This paper addressed this issue by presenting a model named maximum lighting minimum (MNLMAL) based on matrix theory. main idea MNLMAL using as much possible considering supplement. approach first attempt extend concept daylight factor function connect indoor distribution with outdoor illumination. introduces characteristic...

Abstract The phase relations of the R 2 Fe 14 B–Ce B ( = Nd, Pr) pseudobinary systems have been investigated by using X-ray powder diffraction, scanning electron microscopy equipped with energy dispersive spectroscopy and differential thermal analysis. diffraction results show that continuous solid solutions were formed in this systems, all , Ce) belong to tetragonal structure space group P 4 / mnm . With increase Ce content, lattice parameters a c peritectic reaction temperatures decrease...