Phase separation and enhanced wear resistance of Cu88Fe12 immiscible coating prepared by laser cladding

In order to eliminate the microstructure segregation of Cu–Fe immiscible alloys which characterized with a liquid miscible gap, the Cu88Fe12 (wt.%) immiscible coating was prepared by laser cladding. The phase separation characteristic and wear resistance of the Cu88Fe12 (wt.%) immiscible coating were also investigated. The results show that the size of the milled Cu88Fe12 composite powder is reduced comparing to that of the un-milled powder due to fracturing during mechanical milling. Moreover, the demixing or delamination disappears in the Cu88Fe12 immiscible coating and a large amount of face-centered-cubic (fcc) γ-Fe and body-centered-cubic (bcc) α-Fe particles are dispersed in the face-centered-cubic (fcc) ɛ-Cu matrix as a result of liquid phase separation. The size of Fe-rich particles presents an increasing tendency from the bottom to the top of the immiscible coating. As a result, the microhardness of the immiscible coating is improved compared with brass (∼138 HV0.2) due to the presence of high-hardness Fe-rich particles (∼191 HV0.2) and the solid solution strengthening effect of Fe in Cu-rich matrix. Furthermore, the width of ploughing, the width and height of wear scar on the surface of the immiscible coating are much less than those on the surface of brass. Therefore, the wear resistance of the immiscible coating is remarkably enhanced compared with brass

Quasi-4-dimension ionospheric modeling and its application in PPP

The version of record of this article, first published in Satellite Navigation, is available online at Publisher’s website: http://dx.doi.org/10.1186/s43020-022-00085-zIonospheric delay modeling is not only important for GNSS based space weather study and monitoring, but also an efficient tool to overcome the long convergence time of PPP. In this study, a novel model, denoted as Q4DIM (Quasi-4-dimension ionospheric modeling) is proposed for wide-area high precision ionospheric delay correction. In Q4DIM, the LOS (line of sight) ionospheric delay from a GNSS station network is divided into different clusters according to not only latitude and longitude, but also elevation and azimuth. Both GIM (global ionosphere map) and SID (slant ionospheric delay) that traditionally used for wide-area and regional ionospheric delay modeling, respectively, can be regarded as special case of Q4DIM by defining proper grids in latitude, longitude, elevation and azimuth. Thus, Q4DIM presents a resilient model that is capable for both wide-area coverage and high precision. Then four different sets of clusters are defined to illustrate the properties of Q4DIM based on 200 EPN stations. The results suggested that Q4DIM is compatible with the widely acknowledged GIM products. Moreover, it is proved that by inducting the elevation and azimuth angle dependent residuals, the precision of the 2-dimensional GIM-like model, i.e., Q4DIM-2D, is improved from around 1.5 TECU to better than 0.5 TECU. In addition, by treating Q4DIM as a 4-dimensional matrix in latitude, longitude, elevation and azimuth, its sparsity is less than 5%, thus guarantees its feasibility in a bandwidth-sensitive applications, e.g., satellite-based PPP-RTK service. Finally, the advantage of Q4DIM in single frequency PPP over the 2-dimensional models is demonstrated with one month’s data from 30 EPN stations.Peer ReviewedPostprint (published version

Make your own sprites: Aliasing-aware and cell-controllable pixelization

Pixel art is a unique art style with the appearance of low resolution images. In this paper, we propose a data-driven pixelization method that can pro- duce sharp and crisp cell effects with controllable cell sizes. Our approach overcomes the limitation of existing learning-based methods in cell size control by introducing a reference pixel art to explicitly regularize the cell structure. In particular, the cell structure features of the reference pixel art are used as an auxiliary input for the pixelization process, and for measuring the style similarity between the generated result and the reference pixel art. Furthermore, we disentangle the pixelization process into specific cell-aware and aliasing-aware stages, mitigating the ambiguities in joint learning of cell size, aliasing effect, and color assignment. To train our model, we construct a dedicated pixel art dataset and augment it with different cell sizes and different degrees of anti-aliasing effects. Extensive experiments demonstrate its superior performance over state-of-the-arts in terms of cell sharpness and perceptual expressiveness. We also show promising results of video game pixelization for the first time. Code and dataset are available at https://github.com/WuZongWei6/Pixelization

Exploring Barriers and Opportunities in Adopting Crowdsourcing Based New Product Development in Manufacturing SMEs

Crowdsourcing is an innovative business practice of obtaining needed services, ideas, or content or even funds by soliciting contributions from a large group of people (the ‘Crowd’). The potential benefits of utilizing crowdsourcing in product design are well-documented, but little research exists on what are the barriers and opportunities in adopting crowdsourcing in new product development (NPD) of manufacturing SMEs. In order to answer the above questions, a Proof of Market study is carried out on crowdsourcing-based product design under an Innovate UK funded Smart project, which aims at identifying the needs, challenges and future development opportunities associated with adopting crowdsourcing strategies for NPD. The research findings from this study are reported here and can be used to guide future development of crowdsourcing-based collaborative design methods and tools and provide some practical references for industry to adopt this new and emerging collaborative design method in their business

Flow Mechanism of a New Concept Transonic Tandem Fan Stage under the Design and Off-Design Conditions

A detailed numerical simulation of a transonic tandem fan stage was conducted, and the change rule of the flow structure inside the fan stage under the design and off-design conditions was discussed to determine the internal flow mechanisms. The results demonstrate that the total pressure ratio of the fan stage steadily increases with the rotating speed, exhibiting an approximately quadratic growth rate. The peak efficiency reaches the maximum at 80% design speed and rapidly declines under the overspeed condition. Furthermore, the peak efficiency point for different rotating speeds was investigated. The changes in the flow features, such as shock wave/boundary layer interaction and radial migration of low-energy fluids, mainly determine the isentropic efficiency at the higher span. At the middle-lower span, higher or lower inflow relative Mach number increases the flow loss. Moreover, the strength of the tip vortex and wake affect the flow loss at the lower span, while the radial motion of the former flow structure dominated by the equivalent inertial force is another essential factor. Under the high-speed condition, the gain of a high-throughflow fan on choke mass flow can be exhibited. However, the throat position causes an abnormal change under the overspeed condition

Research on Aerodynamic Optimization Method of Multistage Axial Compressor under Multiple Working Conditions Based on Phased Parameterization Strategy

Multistage axial compressor is the key component of aeroengine and gas turbine to realize energy conversion. In order to avoid the “curse of dimensionality” problem in the global optimization process of AL-31F four-stage low-pressure compressor under multiple working conditions, an optimization method based on phased parameterization strategy is proposed. The method uses the idea of “exploration before exploitation” for reference and divides the optimization process into two phases. In the first phase, the traditional parametric modification method based on stacking line is adopted; in the second phase, the full-blade surface parametric modification method with significant low-dimensional characteristics is adopted. Based on the improved artificial bee colony algorithm, a multitask concurrent optimization system is built on the supercomputing platform, and the engineering optimization solution is obtained within 91 hours. The optimization results are as follows: under the condition of meeting the constraints, the adiabatic efficiency is increased by 0.3% and the surge margin is 4.0% at the design speed; the adiabatic efficiency is increased by 0.8% and the surge margin is 2.3% at the off-design speed. These results verify the usefulness and reliability of the optimization method in the field of aerodynamic optimization of a multistage axial flow compressor