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Model-independent constraints on cosmic curvature from strong gravitational lensing and type Ia supernova observations

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arXiv 2019年

作者： Wang, Bo Qi, Jing-Zhao Zhang, Jing-Fei Zhang, Xin Department of Physics College of Sciences Northeastern University Shenyang110819 China Ministry of Education's Key Laboratory of Data Analytics and Optimization for Smart Industry Northeastern University Shenyang110819 China Center for High Energy Physics Peking University Beijing100080 China

Applying the distance sum rule in strong gravitational lensing (SGL) and type Ia supernova (SN Ia) observations, one can provide an interesting cosmological model-independent method to determine the cosmic curvature parameter Ωk. In this paper, with the newly compiled data sets including 161 galactic-scale SGL systems and 1048 SN Ia data, we place constraints on Ωk within the framework of three types of lens models extensively used in SGL studies. Moreover, to investigate the effect of different mass lens samples on the results, we divide the SGL sample into three subsamples based on the center velocity dispersion of intervening galaxies. In the singular isothermal sphere (SIS) and extended power-law lens models, a flat universe is supported with about 20% uncertainty, while a closed universe is preferred in the power-law lens model. We find that the choice of lens models and the classification of SGL data actually can influence the constraints on Ωk significantly. Copyright © 2019, The Authors. All rights reserved.

关键词： Supernovae

Al_xCoCrCuFeNi (X = 0, 0.8) high entropy alloys fabricated by laser powder bed fusion

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Heat Treatment and Surface Engineering 2024年第1期6卷

作者： Feng, Zhengjie Gao, Jingbo Zhang, Deliang School of Materials Science and Engineering Northeastern University Shenyang China National Frontiers Science Center for Industrial Intelligence and Systems Optimization Northeastern University Shenyang China Key Laboratory of Data Analytics and Optimization for Smart Industry (Ministry of Education) Northeastern University Shenyang China

The AlxCoCrCuFeNi (x = 0, 0.8) high entropy alloys (HEAs) were prepared by laser powder bed fusion (LPBF), and the effects of volumetric energy density (VED) and heat treatment on microstructures and mechanical proper... 详细信息

The Al_xCoCrCuFeNi (x = 0, 0.8) high entropy alloys (HEAs) were prepared by laser powder bed fusion (LPBF), and the effects of volumetric energy density (VED) and heat treatment on microstructures and mechanical properties of HEAs were investigated. The results show that the CoCrCuFeNi HEA has a single FCC phase structure and exhibits good ductility. Its yield strength is relatively low, being 520 MPa. After the alloy composition was adjusted from CoCrCuFeNi to Al_0.8CoCrCuFeNi, the HEA changed from FCC single-phase to FCC + BCC dual-phase structure and the hardness and compressive properties were significantly improved. Among them, the Al_0.8CoCrCuFeNi HEA prepared with the VED of 167 J/mm³ has the best mechanical properties, with a compressive yield strength of 652 MPa and good plasticity. After annealing at 600°C and 900°C for 1 h, the mechanical properties of HEAs are significantly improved. In particular, the microhardness and compressive yield strength of the Al_0.8CoCrCuFeNi HEA annealed at 600°C for 1 h are 378 HV and 810 MPa, respectively. The coordinated deformation between FCC and BCC domains, back stress strengthening, solid solution strengthening and precipitation strengthening after heat treatment make the Al_0.8CoCrCuFeNi HEA achieve a balance of high strength and good ductility. © 2024 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.

关键词： heat treatment high entropy alloys Laser powder bed fusion mechanical properties microstructures

Recovery of Lead and Iodine from Spent Perovskite Solar Cells in Molten Salt

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SSRN

SSRN 2022年

作者： Wang, Hongya Chen, Xiang Li, Xianyang Qu, Jiakang Xie, Hongwei Gao, Shuaibo Wang, Dihua Yin, Huayi Key Laboratory for Ecological Metallurgy of Multimetallic Mineral of Ministry of Education School of Metallurgy Northeastern University Shenyang110819 China School of Resource and Environmental Science Wuhan University Wuhan430072 China Key Laboratory of Data Analytics and Optimization for Smart Industry Ministry of Education Northeastern University Shenyang110819 China

Organic-inorganic hybrid perovskite solar cells (PSCs) have received extensive attention due to their high power conversion efficiency, bright prospects for large-scale deployment, and low cost. However, the end-of-life lead (Pb)-based PSC will pose significant resource and environmental challenges. Herein, we develop an eco-friendly strategy, the molten-salt-electrolysis (MSE), to recover Pb and iodine (I2) from spent Pb-based PSC. First, lead iodide (PbI2) was dissolved in molten LiCl-KCl and then electrochemically converted into I2 at a graphite anode and Pb at the cathode. The recovery efficiency of Pb reached 97.65% with a high current efficiency of 96.87%. In addition, a high PbI2 leaching rate of ~ 99.8% and a high PbI2 solubility of ~ 5.97 wt. % in molten LiCl-KCl at 450 oC can sustain a rapid leaching and recovery process. Overall, MSE is a simple, rapid, and environmental-benign method to recover Pb-based PSCs, eliminating the Pb contamination and closing the iodine cycle. © 2022, The Authors. All rights reserved.

关键词： Perovskite

Exploring the key Features of Repeating Fast Radio Bursts with Machine Learning

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arXiv 2024年

作者： Sun, Wan-Peng Zhang, Ji-Guo Li, Yichao Hou, Wan-Ting Zhang, Fu-Wen Zhang, Jing-Fei Zhang, Xin Liaoning Key Laboratory of Cosmology and Astrophysics College of Sciences Northeastern University Shenyang110819 China College of Mathematics and Statistics Liaoning University Shenyang110036 China College of Science Guilin University of Technology Guilin541004 China MOE Key Laboratory of Data Analytics and Optimization for Smart Industry Northeastern University Shenyang110819 China National Frontiers Science Center for Industrial Intelligence and Systems Optimization Northeastern University Shenyang110819 China

Fast radio bursts (FRBs) are enigmatic high-energy events with unknown origins, which are observationally divided into two categories, i.e., repeaters and non-repeaters. However, there are potentially a number of non-repeaters that may be misclassified, as repeating bursts are missed due to the limited sensitivity and observation periods, thus misleading the investigation of their physical properties. In this work, we propose a repeater identification method based on the t-distributed Stochastic Neighbor Embedding algorithm and apply the classification to the first Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst (CHIME/FRB) catalog. We find that the spectral morphology parameters, specifically spectral running (r), represent the key features for identifying repeaters from the non-repeaters. Also, the results suggest that repeaters are more biased toward narrowband emission, whereas non-repeaters are inclined toward broadband emission. We provide a list of 163 repeater candidates, five of which are confirmed with an updated repeater catalog from CHIME/FRB. Our findings improve our understanding of the various properties underlying repeaters and non-repeaters, as well as guidelines for future FRB detection and categorization. Copyright © 2024, The Authors. All rights reserved.

关键词： Radio

Forecast for weighing neutrinos in cosmology with SKA

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arXiv 2019年

作者： Zhang, Jing-Fei Wang, Bo Zhang, Xin Department of Physics College of Sciences Northeastern University Shenyang110819 China Ministry of Education’s Key Laboratory of Data Analytics and Optimization for Smart Industry Northeastern University Shenyang110819 China Center for High Energy Physics Peking University Beijing100080 China

We investigate what role the SKA neutral hydrogen (HI) intensity mapping (IM) and galaxy sky surveys will play in weighing neutrinos in cosmology. We use the simulated data of the baryon acoustic oscillation (BAO) measurements from the HI surveys based on SKA1 (IM) and SKA2 (galaxy) to do the analysis. For the current observations, we use the Planck 2015 cosmic microwave background (CMB) anisotropies observation, the optical BAO measurements, the type Ia supernovae (SN) observation (Pantheon compilation), and the latest H0 measurement. We consider three mass ordering cases for massive neutrinos, i.e., the normal hierarchy (NH), inverted hierarchy (IH), and degenerate hierarchy (DH) cases. It is found that the SKA observation can significantly improve the constraints on Ωm and H0. Compared to the current observation, the SKA1 data can improve the constraints on Ωm by about 33%, and on H0 by about 36%;the SKA2 data can improve the constraints on Ωm by about 58%, and on H0 by about 66%. It is also found that the SKA observation can only slightly improve the constraints on P mν. Compared to the current observation, the SKA1 data can improve the constraints on P mν by about 4%, 3%, and 10%, for the NH, IH, and DH cases, respectively;the SKA2 data can improve the constraints on P mν by about 7%, 7%, and 16%, for the NH, IH, and DH cases, respectively. Copyright © 2019, The Authors. All rights reserved.

关键词： Acoustic intensity measurement

Improving cosmological parameter estimation with the future 21 cm observation from SKA

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arXiv 2019年

作者： Zhang, Jing-Fei Gao, Li-Yang He, Dong-Ze Zhang, Xin Department of Physics College of Sciences Northeastern University Shenyang110819 China Ministry of Education’s Key Laboratory of Data Analytics and Optimization for Smart Industry Northeastern University Shenyang110819 China Center for High Energy Physics Peking University Beijing100080 China

Future observations of 21 cm emission from neutral hydrogen survey will become a promising approach to probe the large scale structure of the Universe. In this paper, we investigate the impacts of Square Kilometre Array (SKA) 21 cm observation on the estimation of cosmological parameters. We use the simulated data of the baryonic acoustic oscillation (BAO) measurements based on the future SKA experiment with the intensity mapping (IM) technique to do the analysis. For the current observations, we use the latest cosmic microwave background (CMB) observation from Planck, the optical BAO measurements, and the Type Ia supernovae (SN) observation (Pantheon compilation). We find that the SKA mock data could break the degeneracy between the matter density and the Hubble constant, further improving the cosmological constraints to a great extent. We also find that the constraint on the equation of state parameters of dark energy could be significantly improved by including the SKA mock data into the cosmological global fit. Copyright © 2019, The Authors. All rights reserved.

关键词： Cosmology

Prospects for improving cosmological parameter estimation with gravitational-wave standard sirens from Taiji

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arXiv 2019年

作者： Zhao, Ze-Wei Wang, Ling-Feng Zhang, Jing-Fei Zhang, Xin Department of Physics College of Sciences Northeastern University Shenyang110819 China Ministry of Education’s Key Laboratory of Data Analytics and Optimization for Smart Industry Northeastern University Shenyang110819 China Center for High Energy Physics Peking University Beijing100080 China

Taiji, a space-based gravitational-wave detector, consists of three satellites forming an equilateral triangle with arm length of 3 × 106 km, orbiting around the Sun. Taiji is able to observe standard siren events of massive black hole binary (MBHB) merger, which is helpful to probe the expansion of the universe. In this paper, we preliminarily forecast the capability of Taiji for improving cosmological parameter estimation with the gravitational-wave standard siren data. We simulate five-year standard siren data based on three fiducial cosmological models and three MBHB growth and formation models. It is found that the standard siren data from Taiji can effectively break the cosmological parameter degeneracies generated by the cosmic microwave background (CMB) anisotropies data, especially for dynamical dark energy models. The constraints on cosmological parameters are significantly improved by the data combination CMB+Taiji, compared to the CMB data alone. Compared to the current optical cosmological observations, Taiji can still provide help in improving the cosmological parameter estimation to some extent. In addition, we consider an ideal scenario to investigate the potential of Taiji on constraining cosmological parameters. We conclude that the standard sirens of MBHB from Taiji will become a powerful cosmological probe in the future. Copyright © 2019, The Authors. All rights reserved.

关键词： Cosmology

Exploiting More Information in Sparse Point Cloud for 3D Single Object Tracking

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arXiv 2022年

作者： Cui, Yubo Shan, Jiayao Gu, Zuoxu Li, Zhiheng Fang, Zheng The Faculty of Robot Science and Engineering Northeastern University Shenyang110819 China The Science and Technology Near-Surface Detection Laboratory Wuxi214000 China The National Frontiers Science Center for Industrial Intelligence and Systems Optimization Shenyang110819 China The The Key Laboratory of Data Analytics and Optimization for Smart Industry Northeastern University Ministry of Education Shenyang110819 China

3D single object tracking is a key task in 3D computer vision. However, the sparsity of point clouds makes it difficult to compute the similarity and locate the object, posing big challenges to the 3D tracker. Previous works tried to solve the problem and improved the tracking performance in some common scenarios, but they usually failed in some extreme sparse scenarios, such as for tracking objects at long distances or partially occluded. To address the above problems, in this paper, we propose a sparse-to-dense and transformer-based framework for 3D single object tracking. First, we transform the 3D sparse points into 3D pillars and then compress them into 2D bird's eye view (BEV) features to have a dense representation. Then, we propose an attention-based encoder to achieve global similarity computation between template and search branches, which could alleviate the influence of sparsity. Meanwhile, the encoder applies the attention on multi-scale features to compensate for the lack of information caused by the sparsity of point cloud and the single scale of features. Finally, we use set-prediction to track the object through a two-stage decoder which also utilizes attention. Extensive experiments show that our method achieves very promising results on the KITTI and NuScenes datasets. Code is available at https://***/3bobo/smat. © 2022, CC BY.

关键词： Signal encoding

Microstructure and mechanical properties of a recycled aluminum alloy fabricated by consolidation of small pieces

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Heat Treatment and Surface Engineering 2024年第1期6卷

作者： Liu, Feifei Zhang, Deliang School of Materials Science and Engineering Northeastern University Shenyang China National Frontiers Science Center for Industrial Intelligence and Systems Optimization Northeastern University Shenyang China Key Laboratory of Data Analytics and Optimization for Smart Industry (Ministry of Education) Northeastern University Shenyang China

The microstructure and mechanical properties of recycled AA6063 aluminum alloy rods fabricated by hot extrusion of forging compacts formed by upsetting compacts of small AA6063 aluminum alloy pieces with different Fe contents before and after T6 heat treatment were studied. In the as-extruded state and with the higher extrusion ratio of 25:1, the microstructure consists of fully recrystallized grains, but the high iron content regions exhibit clearly finer equiaxed grains due to the stronger grain boundary pinning and nucleation effects of a higher number density of Fe-rich phase particles. Increasing the extrusion ratio increases both the strength and ductility of the as-extruded material. The reason is that increasing extrusion ratio enhances the bonding strength of the prior boundaries between the strips formed by deformation of the small pieces. In the T6 heat-treated state, increasing the extrusion ratio from 9:1 to 25:1 clearly increases the fraction of fine and equiaxed grains. The enhancement of the bonding strength and the refinement of the microstructure with the increase of extrusion ratio cause the yield strength and ultimate tensile strength to increase from 174 and 221 MPa to 213 and 237 MPa, respectively, and the elongation to fracture to decrease from 22.1 to 15.4%. Solid-state recycled samples all exhibit a ductile fracture behavior despite formation of microcracks at the prior boundaries. © 2024 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.

关键词： Aluminum alloy hot extrusion mechanical properties microstructure solid state recycling