Investigación sobre la debilidad por fatiga de los nodos de vigas transversales antes y después del refuerzo del puente de acero en celosía

In this research, fatigue tests on full-size specimens are conducted for a steel cross-beam joint before and after reinforcement. Combined with a three-dimensional (3D) numerical simulation, the 3D stress parameters, and their redistribution rules study anew with a web crack and new crack initiation locations and fatigue weakness details are predicted. The research results include the following: 1) The empirical formula parameter m of the Z-axis stress for the new crack tip is approximately 0.05. 2) The fatigue performance of the web’s new crack tips is significantly improved by bolting reinforced steel plates, the stress range is reduced by 60%-98.78%, and the original crack stops growing in size. The health monitoring system can choose the predicted weak details as valid monitoring points so that the fatigue damage can be intelligently perceived after the reinforcement of steel bridges.En este estudio, la prueba de fatiga de una muestra a gran escala antes y después del refuerzo se llevó a cabo en la junta de viga transversal de un puente de acero. Combinado con la simulación numérica 3D, se estudiaron los parámetros de tensión 3D y las leyes de redistribución de las redes agrietadas, y se predijeron nuevas ubicaciones de grietas y detalles débiles por fatiga. Los resultados muestran que el refuerzo de la placa de acero atornillada puede mejorar la resistencia a la fatiga de la viga, y la amplitud de tensión de la punta de grieta de la placa de banda se puede reducir en más del 60%. Los puntos de monitoreo y medición se pueden establecer en los detalles débiles de la predicción, de modo que el daño por fatiga en el funcionamiento del puente de acero en la etapa posterior del refuerzo se encuentre en un estado de percepción inteligente.

Explaining E-Tailers’ Source of Competitiveness: An Integrative Framework

E-tailers refer to small and medium size enterprises or individual entrepreneurs primarily conducting businesses on online shopping platforms. Although many works on e-marketplaces have been done, theory-driven studies that explain e-tailers’ source of competitiveness are relatively scarce. The current work developed an integrative theoretical model in which online social capital, structural assurance, and online word-of-month are proposed to affect e-tailers’ business performance. The current study offers implications on: 1) what are the unique sources of competitiveness for businesses operating in pure online environment; 2) how can the resource-scare e-tailers survive in their rivalry with large offline retailers

SoK: MEV Countermeasures: Theory and Practice

Blockchains offer strong security guarantees, but they cannot protect the ordering of transactions. Powerful players, such as miners, sequencers, and sophisticated bots, can reap significant profits by selectively including, excluding, or re-ordering user transactions. Such profits are called Miner/Maximal Extractable Value or MEV. MEV bears profound implications for blockchain security and decentralization. While numerous countermeasures have been proposed, there is no agreement on the best solution. Moreover, solutions developed in academic literature differ quite drastically from what is widely adopted by practitioners. For these reasons, this paper systematizes the knowledge of the theory and practice of MEV countermeasures. The contribution is twofold. First, we present a comprehensive taxonomy of 28 proposed MEV countermeasures, covering four different technical directions. Secondly, we empirically studied the most popular MEV- auction-based solution with rich blockchain and mempool data. In addition to gaining insights into MEV auction platforms' real-world operations, our study shed light on the prevalent censorship by MEV auction platforms as a result of the recent OFAC sanction, and its implication on blockchain properties

Adaptive Multi-source Predictor for Zero-shot Video Object Segmentation

Static and moving objects often occur in real-life videos. Most video object segmentation methods only focus on extracting and exploiting motion cues to perceive moving objects. Once faced with the frames of static objects, the moving object predictors may predict failed results caused by uncertain motion information, such as low-quality optical flow maps. Besides, different sources such as RGB, depth, optical flow and static saliency can provide useful information about the objects. However, existing approaches only consider either the RGB or RGB and optical flow. In this paper, we propose a novel adaptive multi-source predictor for zero-shot video object segmentation (ZVOS). In the static object predictor, the RGB source is converted to depth and static saliency sources, simultaneously. In the moving object predictor, we propose the multi-source fusion structure. First, the spatial importance of each source is highlighted with the help of the interoceptive spatial attention module (ISAM). Second, the motion-enhanced module (MEM) is designed to generate pure foreground motion attention for improving the representation of static and moving features in the decoder. Furthermore, we design a feature purification module (FPM) to filter the inter-source incompatible features. By using the ISAM, MEM and FPM, the multi-source features are effectively fused. In addition, we put forward an adaptive predictor fusion network (APF) to evaluate the quality of the optical flow map and fuse the predictions from the static object predictor and the moving object predictor in order to prevent over-reliance on the failed results caused by low-quality optical flow maps. Experiments show that the proposed model outperforms the state-of-the-art methods on three challenging ZVOS benchmarks. And, the static object predictor precisely predicts a high-quality depth map and static saliency map at the same time.Comment: Accepted to IJCV 2024. Code is available at: https://github.com/Xiaoqi-Zhao-DLUT/Multi-Source-APS-ZVOS. arXiv admin note: substantial text overlap with arXiv:2108.0507

A Broadband Dual-polarized Capped Bow-tie 2 72 Antenna Array for 28 GHz Band in 5G Systems

With the development of the fifth generation (5G) communications, dual-polarization base station antennas have increasingly attracted a lot of attention. In this paper, a broadband high-gain efficiency dual-polarization polarized capped bow-tie antenna with parasitic directorsarray is presented. Simulation results show that the bandwidth of the proposed antenna is 24-36.8 GHz, with its return loss better than 10 dB and the stable coverage. The directivities vary from 8 to 12dBi and the relative cross-polar level is below -10dB over the most of band. It has a simple and compact structure, and is ready to be extended for an large array antennas with massive MIMO performance used in 5G communications

A Broadband Dual-polarized Capped Bow-tie 2x2 Antenna Array for 28 GHz Band in 5G Systems

With the development of the fifth generation (5G) communications, dual-polarization base station antennas have increasingly attracted a lot of attention. In this paper, a broadband high-efficiency dual-polarized capped bow-tie antenna array is presented. Simulation results show that the bandwidth of the proposed antenna is 24-36.8 GHz, with its return loss better than 10 dB and the stable coverage. The directivities vary from 8 to 12dBi and the relative cross-polar level is below -10dB over the most of band. It has a simple and compact structure, and is ready to be extended for large array antennas with massive MIMO performance used in 5G communications

PLOD1 contributes to proliferation and glycolysis in hepatocellular carcinoma by regulating E2F1

Purpose: To evaluate the effect of procollagen-lysine 1,2-oxoglutarate 5-dioxygenase 1 (PLOD1) in hepatocellular carcinoma (HCC). Methods: HCC cells were subjected to loss of function assays via transfection with siRNA targeting PLOD1. Colony formation and cell counting kit 8 (CCK8) were used to determine cell proliferation. Cell cycle was evaluated by flow cytometry while extracellular acidification rate (ECAR) levels, glucose consumption, and lactate production were determined to investigate aerobic glycolysis. Results: PLOD1 was significantly up-regulated in HCC tissues and cells compared to normal tissues and cells (p < 0.001). Silencing of PLOD1 significantly repressed cell proliferation (p < 0.001) and induced cell cycle arrest in HCC at the G1 phase. ECAR levels, glucose consumption, and lactate production in HCC were reduced by knockdown of PLOD1. Loss of PLOD1 down-regulated the expression of E2F1, while over-expression of E2F1 attenuated PLOD1 knockdown-induced decreases in cell viability, glucose consumption, and lactate production in HCC. Conclusion: Knockdown of PLOD1 inhibits cell proliferation and aerobic glycolysis in HCC via down-regulation of E2F1. Thus, PLOD1 may help in developing an effective strategy for the management of liver cancer

Price Discovery in the Chinese Gold Market

This study conducts price discovery analysis in the Chinese gold market. Our result indicates that the price discovery in Chinese gold market occurs predominantly in the futures market. The result is robust to the different measures of price discovery, namely information share, component share, and information leadership share. Partitioning the daily trades into three trading sessions, we find that the dominance of the futures market occurs in all trading sessions. We further investigate the sequential price discovery within the spot market or futures market. We find that the price discovery of gold spot market and gold futures market occur in the night trading session

Maximizing spin-orbit torque efficiency of Ta(O)/Py via modulating oxygen-induced interface orbital hybridization

Spin-orbit torques due to interfacial Rashba and spin Hall effects have been widely considered as a potentially more efficient approach than the conventional spin-transfer torque to control the magnetization of ferromagnets. We report a comprehensive study of spin-orbit torque efficiency in Ta(O)/Ni81Fe19 bilayers by tuning low-oxidation of \b{eta}-phase tantalum, and find that the spin Hall angle {\theta}DL increases from ~ -0.18 of the pure Ta/Py to the maximum value ~ -0.30 of Ta(O)/Py with 7.8% oxidation. Furthermore, we distinguish the efficiency of the spin-orbit torque generated by the bulk spin Hall effect and by interfacial Rashba effect, respectively, via a series of Py/Cu(0-2 nm)/Ta(O) control experiments. The latter has more than twofold enhancement, and even more significant than that of the former at the optimum oxidation level. Our results indicate that 65% enhancement of the efficiency should be related to the modulation of the interfacial Rashba-like spin-orbit torque due to oxygen-induced orbital hybridization cross the interface. Our results suggest that the modulation of interfacial coupling via oxygen-induced orbital hybridization can be an alternative method to boost the change-spin conversion rate.Comment: 15 pages, 4 figure