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A movable unshielded magnetocardiography system

SCIENCE ADVANCES 2023年第13期9卷 eadg1746页

作者： Xiao, Wei Sun, Chenxi Shen, Liang Feng, Yulong Liu, Meng Wu, Yulong Liu, Xiyu Wu, Teng Peng, Xiang Guo, Hong Peking Univ State Key Lab Adv Opt Commun Syst & Networks Sch Elect Beijing 100871 Peoples R China Peking Univ Ctr Quantum Informat Technol Beijing 100871 Peoples R China

Magnetocardiography (MCG), which uses high-sensitivity magnetometers to record magnetic field signals gen-erated by electrical activity in the heart, is a noninvasive method for evaluating heart diseases such as arrhyth-mia and ischemia. The MCG measurements usually require the participant keeping still in a magnetically shielded room due to the immovable sensor and noisy external environments. These requirements limit MCG applications, such as exercise MCG tests and long-term MCG observations, which are useful for early detections of heart diseases. Here, we introduce a movable MCG system that can clearly record MCG signals of freely be-having participants in an unshielded environment. On the basis of optically pumped magnetometers with a sensitivity of 140 fT/Hz1/2, we successfully demonstrated the resting MCG and the exercise MCG tests. Our method is promising to realize a practical movable multichannel unshielded MCG system that nearly sets no limits to participants and brings another kind of insight into the medical diagnosis of heart disease.

关键词： Magnetocardiography

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The rendering from the periodic system of elements on the stability, elastic, and electronic properties of M2AC phases

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MATERIALIA 2023年 27卷

作者： Wu, Erxiao Zhang, Yiming Li, Mian Li, Youbing Liang, Kun Du, Shiyu Huang, Qing CNiTECH Qianwan Inst Ningbo 315460 Peoples R China

MAX phases are nanolaminated ternary materials that combine metallic and ceramic properties. Currently, the A -site elements replacement in traditional ones by later transition-metals opens a door to explore new types of MAX phases. In this work, we performed a systematic first-principle study to explore trends in stability, electronic structure and elastic properties of 288 compositions of M2AX phases (M=Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W;A=Al, Si, P, S, Ga, Ge, As, Se, In, Sn, Sb, Te, Tl, Pb, Bi, Mn, Fe, Co, Ni, Cu, Zn, Tc, Ru, Rh, Pd, Ag, Cd, Os, Ir, Pt, Au, Hg;X=C). Such a dataset, combined with the rigid-band model been applied to most transition metal carbides, shows us the fundamental trends in bonding mechanisms and elastic properties of MAX phases endowed with the periodic arrangements of M/A-site elements. In particular, the M-A D-d interactions of MAX phases uniquely contribute to the elastic constant C33.

关键词： Max phases formability Periodic system high-throughput calculations Elastic properties

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A Recommendation Strategy Integrating higher-Order Feature Interactions With Knowledge Graphs

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IEEE ACCESS 2022年 10卷 119290-119300页

作者： Lin, Yanru Du, Shiyu Zhang, Yiming Duan, Kai Huang, Qing An, Peng Ningbo Univ Fac Elect Engn & Comp Sci Ningbo 315211 Peoples R China Chinese Acad Sci Ningbo Inst Mat Technol & Engn Engn Lab Adv Energy Mat Ningbo 315201 Peoples R China Ningbo Univ Technol Coll Elect & Informat Engn Ningbo 315211 Zhejiang Peoples R China

Knowledge Graphs (KG) are efficient auxiliary information in recommender systems. However, in knowledge graph feature learning, a major objective is improvement for recommendation performance. One of the problems in the existing methods is that they cannot uncover the deep interaction information of users in a simple way, and this motivates effective learning of the potential embedded information through the knowledge graph. The Graph Convolutional Network (GCN) can be useful for learning information about graph structured data. This paper proposes a method that fuses higher order feature interactions and knowledge graphs and uses them for recommendation. For users, they uses Gated Recurrent Units (GRU) to focus on their preferences so that the ability of convolutional neural networks in processing user preference features is enhanced;for items, the cross-learning module is adopted to learn higher order features between items and entities;for users and entities, KG and user-item interaction information are combined followed by feature extraction of graph structured data by Light GCN, allowing the model to learn potential user-entity associations from the graph structured data. Current experiments on two real datasets show that the proposed model performs better than some recently developed models.

关键词： Recommendation systems knowledge graphs convolutional neural networks

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Performance Evaluation of OFDM System: With and Without Reed-Solomon Codes 4

Performance Evaluation of OFDM System: With and Without Reed...

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4th International Conference on Advances in Computing, Communication Control and Networking, ICAC3N 2022

作者： Rao, Ch. Venkateswara Sankar Miriyala, Ravi Praveena, V. Sri, Vemulapalli Bavya Sri Sailesh A, Bhaavan Ramalakshmi, K. Vishnu Institute of Technology Electronics and Communication Engineering Bhimavaram India Sasi Institute of Technology and Engineering Department of Ece Tadepalligudem India Swarnandhra Institute of Engineering and Technology Department of Ece Narsapur India

ISBN: (纸本)9781665474368

By employing multiple subcarriers within a single channel, Orthogonal Frequency Division Multiplexing (OFDM), a numerical multi-carrier variation method, enlarges the idea of sole subcarrier modulation. Instead of using a single subcarrier to transmit a high-rate stream of data, OFDM incorporated with abundant orthogonal subcarriers that are distributed synchronously. With the help of modulation algorithm (BPSK, QPSK), every subcarrier is modulated at a lower symbol rate. Though within identical bandwidths, the combining of several subcarriers permits data speeds comparable to those of traditional single-carrier modulation techniques. Hence, an efficient channel coding is required for improvising error correction capability in OFDM. Reed Solomon (RS) codes, which have strong error-correcting capabilities, were chosen as an effective channel coding scheme. As a result, the goal of this work is to create a channel coding scheme based on RS code that has been suggested to enhance the performance of OFDM. The proposed scheme has been studied over AWGN fading channel for various modulation techniques. The performance evaluation has been done based on BER analysis of proposed scheme with and without RS channel coding. The simulation results clearly depict that, the BER has been improved for the OFDM with RS channel coding. © 2022 IEEE.

关键词： Orthogonal frequency division multiplexing

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An in-situ study on surface coloring mechanism of a 12Cr ferrite/martensite stainless steel during vacuum heat treatment

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VACUUM 2023年第1期215卷

作者： Wu, Yinze Xia, Shuang Bai, Qin Sun, Wenqiang Wang, Baoshun Zhou, Zhu Liu, Tingguang Shanghai Univ Sch Mat Sci & Engn Shanghai 200444 Peoples R China Shanghai Univ Key Lab Microstruct Shanghai 200444 Peoples R China Shanghai Univ State Key Lab Adv Special Steel Shanghai 200444 Peoples R China Zhejiang Jiuli Hitech Met Co Ltd Huzhou 313028 Peoples R China Engn Res Ctr High Performance Nucl Power Pipe Form Huzhou 313028 Peoples R China Univ Sci & Technol Beijing Natl Ctr Mat Serv Safety Beijing 100083 Peoples R China Shanghai Univ PO Sch Mat Sci & Engn POB 269 149 Yanchang Rd Shanghai 200072 Peoples R China

Color changes during oxidation of a 12Cr ferrite/martensite stainless steel were investigated in-situ by using a high vacuum (5 x 10-3 Pa) heating stage where the high vacuum is provided by an oil diffusion pump. The color of the oxide film changed from initial metallic silver to brown, then consecutively to purple, liberty blue, bluegray and finally to azure blue during the 90 min heat treatment at 690 & DEG;C in high vacuum. In contrast to the above changes, during oxidation at 1130 & DEG;C, the color changes from metallic silver to brown, then to various blue and finally changed back to metallic silver. The color as a result of thin-film interference mainly depended on the oxide film thickness. The significant reduction of the thickness of the oxide film on the sample vacuum heattreated at 1130 celcius is owing to the volatilization of oxide, which is a result of the reaction of the already formed Cr2O3 with residual water vapor and oxygen to generate CrO2(OH)2 and CrO3 gas, which evaporated from the surface at 1130 & DEG;C. Ferrite grains have a much lower oxidation kinetics than that of martensite.

关键词： Stainless steel Vacuum heat treatment In-situ oxidation Coloring mechanism X-ray photoelectron spectroscopy

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Active stabilization of terrestrial magnetic field with potassium atomic magnetometer

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REVIEW OF SCIENTIFIC INSTRUMENTS 2022年第1期93卷 015003-015003页

作者： Ding, Yudong Zhang, Rui Zheng, Junhe Chen, Jingbiao Peng, Xiang Wu, Teng Guo, Hong Peking Univ Sch Elect State Key Lab Adv Opt Commun Syst & Networks Beijing 100871 Peoples R China Peking Univ Ctr Quantum Informat Technol Beijing 100871 Peoples R China Beijing Acad Quantum Informat Sci Beijing 100193 Peoples R China

This paper introduces a magnetically quiet environment where the magnetic-field noise is actively suppressed using an optically pumped potassium magnetometer. In a large dynamic range of Earth's magnetic fields, the magnetic-resonance signals of potassium are completely separated in frequency, and we experimentally demonstrate that one of them could be used to measure and compensate magnetic-field noise. The magnetic-field noise floor after stabilization is & SIM;100 fT/vHz under a bias field ranging from 20 to 100 mu T. This method could be useful for fundamental-physics experiments and biomedical sciences where a large dynamic range of quiet magnetic fields is needed.

关键词： Potassium

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Structural, Electronic, and Mechanical Properties of Zr2SeB and Zr2SeN from First-Principle Investigations

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MATERIALS 2023年第15期16卷 5455-5455页

作者： Bai, Xiaojing Chen, Ke Luo, Kan Qiu, Nianxiang Huang, Qing Han, Qi Liang, Haijing Zhang, Xiaohong Bai, Chengying Anyang Inst Technol Sch Mat Sci & Engn Anyang 455000 Peoples R China Chinese Acad Sci Ningbo Inst Mat Technol & Engn Engn Lab Adv Energy Mat Ningbo 315201 Peoples R China Ningbo Univ Coll Sci & Technol Ningbo 315300 Peoples R China China Univ Petr Sch Mat Sci & Engn Qingdao 266580 Peoples R China Harbin Engn Univ Coll Mat Sci & Chem Engn Key Lab Superlight Mat & Surface Technol Minist Educ Harbin 150001 Peoples R China

MAX phases have exhibited diverse physical properties, inspiring their promising applications in several important research fields. The introduction of a chalcogen atom into a phase of MAX has further facilitated the modulation of their physical properties and the extension of MAX family diversity. The physical characteristics of the novel chalcogen-containing MAX 211 phase Zr2SeB and Zr2SeN have been systematically investigated. The present investigation is conducted from a multi-faceted perspective that encompasses the stability, electronic structure, and mechanical properties of the system, via the employment of the first-principles density functional theory methodology. By replacing C with B/N in the chalcogen-containing MAX phase, it has been shown that their corresponding mechanical properties are appropriately tuned, which may offer a way to design novel MAX phase materials with enriched properties. In order to assess the dynamical and mechanical stability of the systems under investigation, a thorough evaluation has been carried out based on the analysis of phonon dispersions and elastic constants conditions. The predicted results reveal a strong interaction between zirconium and boron or nitrogen within the structures of Zr2SeB and Zr2SeN. The calculated band structures and electronic density of states for Zr2SeB and Zr2SeN demonstrate their metallic nature and anisotropic conductivity. The theoretically estimated Pugh and Poisson ratios imply that these phases are characterized by brittleness.

关键词： first principles Zr2SeB N electronic properties mechanical properties

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Optimization of thermodynamic performance and mass evaluation for MW-class space nuclear reactor coupled with noble gas binary mixtures Brayton cycle

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ENERGY 2024年 293卷

作者： Ma, Wenkui Ye, Ping Gao, Yue Hao, Yadong Yang, Xiaoyong Tsinghua Univ Collaborat Innovat Ctr Adv Nucl Energy Technol Key Lab Adv Reactor Engn & Safety Inst Nucl & New Energy TechnolMinist Educ Beijing 100084 Peoples R China

Space exploration technology is an important indicator of society's technological level. A space reactor coupled with a Brayton cycle is preferable for megawatt -scale space power systems. Noble gas binary mixtures have high chemical stability, heat transfer performance, and compressibility, making them the principal choice of working fluid for the space reactor Brayton cycle, which is also the key factor affecting the thermodynamic performance and mass of the system. This study developed thermodynamic performance and mass evaluation models for the space nuclear Brayton cycle and discovered the inherent relationship between system thermodynamic performance and mass. The effects of noble gas binary mixtures on system performance and mass were investigated. The results indicated that the elevated molar mass of noble gas binary mixtures reduced the aerodynamic load and mass of the turbomachines and increased the mass of the recuperator. There are optimal values of the total mass, specific mass of the system, and working fluid composition. Helium -xenon mixture is the optimal working fluid because it can achieve the highest thermodynamic efficiency and lowest mass. Furthermore, the optimal scheme of the helium -xenon Brayton cycle for a space nuclear power system was obtained by multi -objective optimization. Its power generation efficiency, specific mass, and helium molar fraction in the helium -xenon working fluid are 29.04%, 5.65 t center dot MW- 1 and 77.5%, respectively. This study provides a reference for the design and optimization of space nuclear power systems.

关键词： Space reactor Brayton cycle Thermodynamic performance Specific mass Noble gas binary mixtures

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Whole-genome resequencing reveals loci under selection during silkworm improvement

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JOURNAL OF ANIMAL BREEDING AND GENETICS 2021年第3期138卷 278-290页

作者： Li, Chunlin Zuo, Weidong Tong, Xiaoling Han, Minjin Gao, Rui Hu, Hai Lu, Kunpeng Luan, Yue Zhang, Bili Liu, Yanyu Dai, Fangyin Southwest Univ Coll Biotechnol State Key Lab Silkworm Genome Biol Key Lab Sericultural Biol & Genet BreedingMinist Chongqing 400715 Peoples R China

Breeding or genetic improvement refers to the process of artificial selection following domestication;as such, it has had a major influence on modern agriculture and animal production. Improvement generally focuses on traits that greatly affect the economic performance. Therefore, understanding the genetic basis underlying improvement will contribute to the identification of genes controlling economic traits and will facilitate future crop and animal breeding. However, genome-wide study of the molecular basis underlying improvement remains rare. The silkworm is a unique, entirely domesticated economically important invertebrate;genetic improvement has had a huge effect on the silkworm regarding silk-related traits. Herein, we performed whole-genomic sequencing on local and genetically improved silkworm lines to identify the genomic regions under strong selection in silkworm breeding/improvement. By genomic-wide selective sweeping analysis, we identified 24 genomic regions with strong selection signals, eight of which contained 13 candidate genes underlying silkworm breeding. Interestingly, six of these genes were annotated with functions related to neural signal response. Among the six genes,BGIBMGA004050encodes silkwormCREB-regulated_transcription_coactivator_1(BmCRTC1), which was reported to be involved in energy-sensing pathways. These results suggested that improvement may have affected the nervous system of the silkworm. This research will provide new insights into the genetic basis underlying the genetic improvement of silkworms and possibly of other species.

关键词： BmCRTC1 genetic improvement nervous system selective sweeping silkworm

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Structure and Properties of Bombyx Mandarina Silk Fiber and Hybrid Silk Fiber

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JOURNAL OF NATURAL FIBERS 2021年第3期18卷 330-342页

作者： Deng, Tingting Cheng, Lan Peng, Yunwu Tong, Xiaoling Guo, Nangkuo Li, Zhi Zhao, Tianfu Dai, Fangyin Southwest Univ State Key Lab Silkworm Genome Biol Key Lab Sericultural Biol & Genet Breeding Minist AgrColl Biotechnol Chongqing 400715 Peoples R China Southwest Univ Chongqing Engn Res Ctr Biomat Fiber & Modern Text Coll Text & Garment Chongqing Peoples R China Ankang Coll Ankang Peoples R China

Bombyx mandarina silk fibers, as a precious resource of wild silk fibers, have some different characteristics to Bombyx mori silk fibers. To make a better use of this precious green material in various fields, it is necessary to investigate the characteristics of the fibers. In this research, the structure and properties of Bombyx mori silk fiber, Hybrid silk fiber, and Bombyx mandarina silk fiber are studied and analyzed. In terms of secondary structure, beta-sheet structures are dominant in all three fibers while random coil and alpha-helix structures account for smaller portions of the fibers. Bombyx mandarina silk fiber exhibits a characteristic of amino acid distribution where the content of glycine is higher than that of alanine. The further analysis indicates the breaking strength of B. mandarina silk fibers is superior to that of B. mori silk fiber although Bombyx mandarina silk fiber is finer than Bombyx mori silk fiber. Our investigations provide a significant guide in the development and utilization of these precious silk resources, and Bombyx mandarina and Hybrid silk fibers show good potential for application in the same fields as Bombyx mori silk fibers.

关键词： Bombyx mandarina silk fiber hybrid silk fiber structure property

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