The Research of Simulation on Eddy Current Separation Process Based on MATLAB and COMSOL

AbstractThe separation process of eddy current separator is effected by the structure parameters of magnetic roller, the working parameters of the separator and some parameters of the scrap metal, such as the material, the shape, the size and so on. This is a complex process of electric field and magnetic field coupling. During this process, the sorting function of separator is powered by the existence of the eddy current power in waste particles, and the separation effect is directly determined by the flying distance of the scrap metal in the separation process. This paper armed for studying the eddy current power and the flying distance of the waste particles in separation to realize the simulation of the separation process. The eddy current force was obtained by the finite element analysis of the magnetic roller based on COMSOL, and the flying distance was got by the joint simulation of COMSOL and MATLAB

Loop closure detection of visual SLAM based on variational autoencoder

Loop closure detection is an important module for simultaneous localization and mapping (SLAM). Correct detection of loops can reduce the cumulative drift in positioning. Because traditional detection methods rely on handicraft features, false positive detections can occur when the environment changes, resulting in incorrect estimates and an inability to obtain accurate maps. In this research paper, a loop closure detection method based on a variational autoencoder (VAE) is proposed. It is intended to be used as a feature extractor to extract image features through neural networks to replace the handicraft features used in traditional methods. This method extracts a low-dimensional vector as the representation of the image. At the same time, the attention mechanism is added to the network and constraints are added to improve the loss function for better image representation. In the back-end feature matching process, geometric checking is used to filter out the wrong matching for the false positive problem. Finally, through numerical experiments, the proposed method is demonstrated to have a better precision-recall curve than the traditional method of the bag-of-words model and other deep learning methods and is highly robust to environmental changes. In addition, experiments on datasets from three different scenarios also demonstrate that the method can be applied in real-world scenarios and that it has a good performance

The impact of university STEM assets:A systematic review of the empirical evidence

Background Innovation ecosystems are an important driver of regional economic growth and development. STEM assets connected to universities may play an important role in such ecosystems. Objective To systematically review the literature relating to the effect of university STEM assets on regional economies and innovation ecosystems, providing a better understanding of how the impact is generated and constrained, as well as identifying any gaps in knowledge. Methods Keyword and text word searches using the Web of Science Core Collection (Clarivate), Econlit (EBSCO) and ERIC (EBSCO) were performed in July 2021 and February 2023. Papers were double screened on abstract and title, and were included if there was consensus that they fulfilled the inclusion criteria of: (i) relating to an OECD country; (ii) having been published between 1 January 2010 and 28 February 2023; and (iii) concerning the impact of STEM assets. Data extraction was undertaken for each article by a single reviewer and checked by a second reviewer. Due to the heterogeneity of the study designs and outcome measures used, it was not possible to perform a quantitative synthesis of results. A narrative synthesis was subsequently undertaken. Results Of the 162 articles identified for detailed review, 34 were accepted as being sufficiently relevant to the study to be included for final analysis. Three important features identified were that the literature: i) is predominately concerned with supporting new businesses; ii) describes a high level of involvement with a university in providing that support; and iii studies economic impacts at local, regional and national levels. Discussion The evidence points to a gap in the literature relating to looking at the broader impact of STEM assets and any corresponding transformational, system-level effects that go beyond narrowly defined, short to medium-term outcomes. The main limitation of this review is that information on STEM assets in the non-academic literature is not captured

Droplet-like Fermi surfaces in the anti-ferromagnetic phase of EuFe2_2As2_2, an Fe-pnictide superconductor parent compound

Using angle resolved photoemission it is shown that the low lying electronic states of the iron pnictide parent compound EuFe$_2$As$_2$ are strongly modified in the magnetically ordered, low temperature, orthorhombic state compared to the tetragonal, paramagnetic case above the spin density wave transition temperature. Back-folded bands, reflected in the orthorhombic/ anti-ferromagnetic Brillouin zone boundary hybridize strongly with the non-folded states, leading to the opening of energy gaps. As a direct consequence, the large Fermi surfaces of the tetragonal phase fragment, the low temperature Fermi surface being comprised of small droplets, built up of electron and hole-like sections. These high resolution ARPES data are therefore in keeping with quantum oscillation and optical data from other undoped pnictide parent compounds.Comment: 4 figures, 6 page

Pairing symmetry and properties of iron-based high temperature superconductors

Pairing symmetry is important to indentify the pairing mechanism. The analysis becomes particularly timely and important for the newly discovered iron-based multi-orbital superconductors. From group theory point of view we classified all pairing matrices (in the orbital space) that carry irreducible representations of the system. The quasiparticle gap falls into three categories: full, nodal and gapless. The nodal-gap states show conventional Volovik effect even for on-site pairing. The gapless states are odd in orbital space, have a negative superfluid density and are therefore unstable. In connection to experiments we proposed possible pairing states and implications for the pairing mechanism.Comment: 4 pages, 1 table, 2 figures, polished versio

Research on Behavior Cause of Limited Space Accident Based on “2-4” Model

In order to prevent accidental casualties in the course of limited space operation, the behavioral safety “2-4” model is used to study the behavioral causes of typical limited space operation accidents. First, the causes of one-time and habitual behavior are studied from the individual level, that is, unsafe action, physical state and safety knowledge, consciousness; then, the research of operational behavior and guiding behavior is studied from the organizational level. Finally, the prevention and control suggestions are put forward to reduce the occurrence of such accidents