Crack Growth Rate Model under Constant Cyclic Loading and Effect of Different Singularity Fields

AbstractThe effect of two singularity fields: the Hutchinson-Rice-Rosengren (HRR) fields and the Rice-Kujawski-Ellyin (RKE) fields, is investigated in the present study to discuss a former fatigue crack growth (FCG) model based on energy balance during growth of the crack. A parameter which can demonstrates the effect of different types of singularity fields is included in the crack propagation model which can predict stage-II FCG behavior independently from the basic low cycle fatigue properties. Good agreement between experimental and theoretical results is obtained

Motion-corrected Fourier ptychography

Fourier ptychography (FP) is a recently proposed computational imaging technique for high space-bandwidth product imaging. In real setups such as endoscope and transmission electron microscope, the common sample motion largely degrades the FP reconstruction and limits its practicability. In this paper, we propose a novel FP reconstruction method to efficiently correct for unknown sample motion. Specifically, we adaptively update the sample's Fourier spectrum from low spatial-frequency regions towards high spatial-frequency ones, with an additional motion recovery and phase-offset compensation procedure for each sub-spectrum. Benefiting from the phase retrieval redundancy theory, the required large overlap between adjacent sub-spectra offers an accurate guide for successful motion recovery. Experimental results on both simulated data and real captured data show that the proposed method can correct for unknown sample motion with its standard deviation being up to 10% of the field-of-view scale. We have released our source code for non-commercial use, and it may find wide applications in related FP platforms such as endoscopy and transmission electron microscopy

An Empirical Study of China-Australia Bilateral Trade Potential Based on Gravity Model

Based on the use of trade integration index and gravity model, this paper uses the bilateral goods trade data between China and Australia from 2000 to 2019 to analyze the trade status, trade complementarity and trade potential between China and Australia. The results of the study show that the trade scale, trade complementarity and trade potential between China and Australia are constantly expanding. However, from the perspective of trade balance, China has always been in the position of a deficit country, and the deficit is getting larger and larger, especially in terms of primary products. Judging from the trade integration index, China’s trade integration with Australia generally shows an upward trend, indicating that the trade dependence between China and Australia is gradually increasing. Judging from the results of the trade potential analysis, the trade potential between the two countries has not been fully realized, and there is still much room for improvement in bilateral trade relations

Enterprise’s Strategies to Deal with Epidemic Crisis Based on Super-Dynamic Capability Theory

In this paper, the supply chain management risks arising from 2019-novel coronavirus (hereinafter referred to as “COVID-19”) outbreak was proposed, and they were further analyzed from three main aspects such as change in demand conditions of domestic customers, change in domestic supply market, impact on domestic logistics industry. Besides, multiple feasible strategies for coping with such epidemic situation were proposed for enterprises based on the super-dynamic capability theory. The research in this paper has powerful theoretical value and practical significance for the current development of enterprises, especially the reorganization of enterprises under the current epidemic crisis in China

Development Status and Business Solution of Ultra-high Pressure Food

Ultra-high pressure food processing technology refers to the technology of sterilizing food under thousands of atmospheric pressure without destroying the properties of food raw materials. Japan is a world leader in HPP technology. Significant achievements have been made in experimental equipment, production equipment, processing, sterilization and preservation of ultra-high pressure technology. Almost all natural, safe and healthy HPP food jams and fruit juices have been commercialized. Germany, the United States, France, the United Kingdom and other countries are also unwilling to fall behind, they are scrambling to carry out research on ultra-high voltage technology and have achieved industrialization results.China’s research on food ultra-high pressure technology started late. After nearly ten years of technical digestion and research, the research results have been achieved in stages, but there is still a large gap compared with developed countries. This article outlines the application of HPP technology in food processing, briefly analyzes the development of HPP food technology in China today, and establishes a cold chain supply chain model to identify problems and propose certain countermeasures, with a view to addressing HPP technology in food and chemicals industry

Image Encoding Using Multi-Level DNA Barcodes with Nanopore Readout.

Deoxyribonucleic acid (DNA) nanostructure-based data encoding is an emerging information storage mode, offering rewritable, editable, and secure data storage. Herein, a DNA nanostructure-based storage method established on a solid-state nanopore sensing platform to save and encrypt a 2D grayscale image is proposed. DNA multi-way junctions of different sizes are attached to a double strand of DNA carriers, resulting in distinct levels of current blockades when passing through a glass nanopore with diameters around 14 nm. The resulting quaternary encoding doubles the capacity relative to a classical binary system. Through toehold-mediated strand displacement reactions, the DNA nanostructures can be precisely added to and removed from the DNA carrier. By encoding the image into 16 DNA carriers using the quaternary barcodes and reading them in one simultaneous measurement, the image is successfully saved, encrypted, and recovered. Avoiding any proteins or enzymatic reactions, the authors thus realize a pure DNA storage system on a nanopore platform with increased capacity and programmability

Angular deviation and diffraction efficiency of Littrow-configuration ECDL for three-dimensional diffraction

We consider in this paper the angular deviation and diffraction efficiency of the reflection gratings in Littrow-configuration for applications of external cavity diode laser (ECDL) using the rigorous coupled-wave analysis (RCWA) method. We consider the three-dimensional diffraction case in general, where the incidence plane is un-parallel with the grating vector (i.e. conical diffraction). The angular tolerance of arbitrary gratings under plane and conical diffraction are thus derived and presented. A typical blazed grating is chosen as an example to calculate its diffraction efficiency (DE) using RCWA. {Furthermore}, we point out that the angular tolerance and reflection efficiency can be improved if the appropriate parameter settings are selected for Littrow-configuration ECDL, including incidence angle, diffraction order, grating period and blazed angle. Otherwise, a tiny slanting angle of the grating vector deviated from the incidence plane will {deviate the feedback light away from} entering the LD-chip and halt laser oscillation in the external cavity. Finally, a general rule for the parameter settings in Littrow-configuration is provided as a benchmark.Comment: 9 pages,11 figure

Multiagent-Based Reactive Power Sharing and Control Model for Islanded Microgrids

In islanded microgrids (MGs), the reactive power cannot be shared proportionally among distributed generators (DGs) with conventional droop control, due to the mismatch in feeder impedances. For the purpose of proportional reactive power sharing, a multiagent system (MAS)-based distributed control model for droop-controlled MGs is proposed. The proposed control model consists of two layers, where the bottom layer is the electrical distribution MG, while the top layer is a communication network composed of agents. Moreover, agents on the communication network exchange the information acquired from DGs with neighbors, and calculate set points for DGs they connect to, according to the control laws. Furthermore, a theorem is demonstrated, which yields a systematic method to derive the control laws from a given communication network. Finally, three cases are carried out to test the performance of the control model, in which the uncertainty of intermittent DGs, variations in load demands, as well as impacts of time delays are considered. The simulation results demonstrate the effectiveness of the control model in proportional reactive power sharing, and the plug and play capability of the control model is also verified.Feixiong Chen, Minyou Chen, Qiang Li, Kaikai Meng, Josep M. Guerrero, Fellow and Derek Abbot