Research of TE behaviour and compression property of porous Ni–Al–Cr intermetallic compounds in the β phase region

Ni–Al–Cr alloys in the β phase (B2–NiAl) region exhibit remarkable stability and mechanical property. Through thermal explosion (TE) reaction, Ni–Al–Cr intermetallic compounds with high porosity can be obtained. In this study, the focus lies on analyzing the macroscopic morphology, microstructure, phase distribution, TE behaviour, and the mechanical property of porous Ni–Al–Cr in the β phase region. Following the TE reaction, the Al-rich sintered product demonstrates a uniform phase composition and high porosity, reaching 44.39%. The vigorous TE reaction promotes the formation of interconnected pores, while the high porosity structure compromises the mechanical properties of the sample. Conversely, the Al-poor sintered product, due to a moderate TE reaction and low porosity structure, maintains its complete morphology and exhibits excellent compression resistance (yield stress reaching 538 MPa). This study offers valuable insights for the fabrication of porous Ni–Al–Cr materials with exceptional structure and performance

Microstructure and mechanical properties of directionally solidified alloys of Mg-9Zn-2Y

Samples of directionally solidified Mg-9Zn-2Y alloys have been obtained using vacuum induced directional solidification equipment. The metallographic structures and mechanical properties at room and high temperatures of the directionally solidified alloys have been investigated and compared with those of conventional casting alloys. The structures have consisted of columnar crystals with a specific orientation, and the parallel phases near the grain boundaries and inside the grains have quasi-crystals of I-Mg3Zn6Y. At room temperature, the maximum compressive resistance and section expansion ratio of the directionally solidified alloys have been 54 and 31% higher, respectively, than those of the conventional casting alloys. The peak stress of the directionally solidified alloys has found 238 MPa, which is 57% higher than that of the conventional casting alloys (152 MPa) at 200 C with a strain rate of 0.1 s-1. In addition, the peak stress was 140 MPa at 300 C with a strain rate of 0.1s-1, while it was only 84 MPa for the conventional casting alloys. Therefore, the directionally solidified alloys has higher strength and plasticity at room temperature and improved mechanical properties at a high temperature

AcoMYB4, an Ananas comosus L. MYB transcription factor, functions in osmotic stress through negative regulation of ABA signaling

Drought and salt stress are the main environmental cues affecting the survival, development, distribution, and yield of crops worldwide. MYB transcription factors play a crucial role in plants’ biological processes, but the function of pineapple MYB genes is still obscure. In this study, one of the pineapple MYB transcription factors, AcoMYB4, was isolated and characterized. The results showed that AcoMYB4 is localized in the cell nucleus, and its expression is induced by low temperature, drought, salt stress, and hormonal stimulation, especially by abscisic acid (ABA). Overexpression of AcoMYB4 in rice and Arabidopsis enhanced plant sensitivity to osmotic stress; it led to an increase in the number stomata on leaf surfaces and lower germination rate under salt and drought stress. Furthermore, in AcoMYB4 OE lines, the membrane oxidation index, free proline, and soluble sugar contents were decreased. In contrast, electrolyte leakage and malondialdehyde (MDA) content increased significantly due to membrane injury, indicating higher sensitivity to drought and salinity stresses. Besides the above, both the expression level and activities of several antioxidant enzymes were decreased, indicating lower antioxidant activity in AcoMYB4 transgenic plants. Moreover, under osmotic stress, overexpression of AcoMYB4 inhibited ABA biosynthesis through a decrease in the transcription of genes responsible for ABA synthesis (ABA1 and ABA2) and ABA signal transduction factor ABI5. These results suggest that AcoMYB4 negatively regulates osmotic stress by attenuating cellular ABA biosynthesis and signal transduction pathways

Microstructure and mechanical properties of directionally solidified alloys of Mg-9Zn-2Y

573-578Samples of directionally solidified Mg-9Zn-2Y alloys have been obtained using vacuum induced directional solidification equipment. The metallographic structures and mechanical properties at room and high temperatures of the directionally solidified alloys have been investigated and compared with those of conventional casting alloys. The structures have consisted of columnar crystals with a specific orientation, and the parallel phases near the grain boundaries and inside the grains have quasi-crystals of I-Mg3Zn6Y. At room temperature, the maximum compressive resistance and section expansion ratio of the directionally solidified alloys have been 54 and 31% higher, respectively, than those of the conventional casting alloys. The peak stress of the directionally solidified alloys has found 238 MPa, which is 57% higher than that of the conventional casting alloys (152 MPa) at 200 °C with a strain rate of 0.1 s-1. In addition, the peak stress was 140 MPa at 300 °C with a strain rate of 0.1s-1, while it was only 84 MPa for the conventional casting alloys. Therefore, the directionally solidified alloys has higher strength and plasticity at room temperature and improved mechanical properties at a high temperature

Online IMU Self-Calibration for Visual-Inertial Systems

Low-cost microelectro mechanical systems (MEMS)-based inertial measurement unit (IMU) measurements are usually affected by inaccurate scale factors, axis misalignments, and g-sensitivity errors. These errors may significantly influence the performance of visual-inertial methods. In this paper, we propose an online IMU self-calibration method for visual-inertial systems equipped with a low-cost inertial sensor. The goal of our method is to concurrently perform 3D pose estimation and online IMU calibration based on optimization methods in unknown environments without any external equipment. To achieve this goal, we firstly develop a novel preintegration method that can handle the IMU intrinsic parameters error propagation. Then, we frame IMU calibration problem into general factors so that we can easily integrate the factors into the current graph-based visual-inertial frameworks and jointly optimize the IMU intrinsic parameters as well as the system states in a big bundle. We evaluate the proposed method with a publicly available dataset. Experimental results verify that the proposed approach is able to accurately calibrate all the considered parameters in real time, leading to significant improvement of estimation precision of visual-inertial system (VINS) compared with the estimation results with offline precalibrated IMU measurements

Vertically integrated outdoor in-site line protection based on SoC technique

By focusing on the problems of speed, reliability, operation and maintenance in the practical application of line protection in conventional and smart substations, we propose system architecture and a technical scheme for in-site (similar in meaning to on-site or near-process) line protection based on vertical integration and outdoor installation. The functions of the single-bay merging unit, relay protection, and intelligent terminal are vertically integrated to reduce the number and types of devices, simplify the configuration, reduce signal transmission, and shorten the protection action time. In addition, this vertically integrated device is applied to provide data acquisition and control execution support for substation-area protection, security and stability of devices, and other substation-area devices. The vital performance outputs are tested and compared. Finally, the experimental results verify that the proposed scheme is feasible and the technology is advanced. Keywords: Line protection, In-site relay protection, Merging unit, Vertical integratio