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20th CIRP Conference on Electro Physical and Chemical Machining, ISEM 2020

作者： Fu, Yulei Hu, Jing Zhao, Wansheng Peng, Fujun Huo, Weijie Cao, Xiaotong Shanghai Institute of Aerospace System Engineering Space Structure and Mechanism Technology Laboratory of China Aerospace Science and Technology Group Co.Ltd NO. 3888 Yuanjiang Road Shanghai201109 China School of Mechanical Engineering Shanghai Jiao Tong University No. 800 Dongchuan Road Shanghai200240 China

Pseudospark electron beam is a kind of high-current pulsed electron beam. It is characterized by high current (hundreds of amperes to thousands amperes), short pulse duration (hundreds of nanoseconds to thousands nanoseconds), high frequency (hundreds Hz to thousands Hz) and self-focused beam diameter (typically 0.5-5 mm), which are more favorable for metal surface treatment compared with the conventional thermal-emission electron beam diode. The pseudospark electron beam is easy to achieve high rate of beam energy rise, plasma quenching and to obtain fast and stable repetitive operation. Some unique properties of material processing applications have been induced by the pseudospark electron beam treatment. In this paper, the mechanism and microstructure modification of AISI1045 steel by pseudospark electron beam surface treatment have been investigated. Surface microstructure and chemical composition of AISI 1045 steel pre and post pseudospark electron beam treatment are investigated by using scanning electron microscope (SEM), electron back-scattered diffraction (EBSD) and transmission electron microscope (TEM). Results show that the average depth of the treated layer is several microns. The melt interface is not straight, indicating a non-uniform melting process. Besides, material's grain size is significantly reduced after pseudospark treatment, especially in sublayer. The average grain size in the sublayer is smaller than in the top-layer. The relatively finer grain size in the sublayer is attributed to the temperature-induced dynamic thermal stress fields and the highest temperature gradient in the subsurface layer instead of on the top layer. Furthermore, the amorphous phase is observed on the surface of melted layer. © 2020 The Authors. Published by Elsevier B.V.

关键词： Microstructure

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First Principles Calculations of Charge Shift Photocurrent in Vdws Slide Double Layered 2d H-Bn and Β-Ges Homostructures

SSRN

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SSRN 2022年

作者： Kaner, Ngeywo Tolbert Wei, Yadong Raza, Ali Yang, Jianqun Li, Xingji Li, Weiqi Jiang, YongYuan Wei Quan, Tian School of Physics Harbin Institute of Technology Harbin150001 China School of Materials Science and Engineering Harbin Institute of Technology Harbin150001 China Technology Innovation Center of Materials and Devices at Extreme Environment Harbin Institute of Technology Harbin150001 China 1-Km Main Daska Road Punjab Sialkot51040 Pakistan State Key Laboratory of Intense Pulsed Radiation Simulation and Effect Xi’an710024 China Key Lab of Micro-Optics and Photonic Technology of Heilongjiang Province Harbin150001 China Key Laboratory of Micro-Nano Optoelectronic Information System Ministry of Industry and Information Technology Harbin150001 China Collaborative Innovation Center of Extreme Optics Shanxi University Taiyuan030006 China Chongqing Key Laboratory of Theoretical and Computational Chemistry College of Chemistry and Chemical Engineering Chongqing University Chongqing401331 China

Shift photovoltaic current (SPC) in polar non-centrosymmetric materials has recently emerged as a promising candidate for the next generation photovoltaic devices in which Shockley-Queisser limits are fully overcome. Here, we apply first principles calculations to predict colossal SPC in the slide bilayers of 2D h -BN and β-GeS vdW homostructures. The large SPC in slide bilayers h -BN and β-GeS reaches 49.3 µAV-2 and 130µ µAV-2 , respectively, in the ultra-violet (UV) region. Increasing the number of layers is further implemented to tune the band structure of the two homostructures. Consequently, giant SPC peaks about 3 times larger than those of the 2-layers is predicted at photon energies 7.40 eV and 5.95 eV in the 5-layers of h -BN and β-GeS, respectively. The two homostructures may thus be promising building blocks for next-generation shift current devices. These findings also suggest layering as a possible convenient approach of enhancing and also tuning the SPC output in thin layered materials. © 2022, The Authors. All rights reserved.

关键词： Van der Waals forces

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Hardware architecture design of HEVC entropy decoding

Hardware architecture design of HEVC entropy decoding

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IEEE International Conference on Big Data and Cloud Computing (BdCloud)

作者： Shiyu Wang Shengbing Zhang Jihe Wang Libo Chang Liangyou Feng Xiaoya Fan Engineering Research Center of Embedded System Integration Ministry of Education School of Computer Science Northwestern Polytechnical University Xian China National Engineering Laboratory for Integrated Aero-Space-Ground-Ocean Big Data Application Technology School of Computer Science Northwestern Polytechnical University Xian China

As the latest generation of digital video coding standard, HEVC has technically optimized multiple modules such as related frame prediction, block processing and entropy coding in the frequency coding and decoding framework. However, flexible and efficient coding algorithms make the amount of calculation in the video decoding and reconstruction process increase dramatically. The energy efficiency of traditional processors is limited, and the decoding calculation process is difficult to meet the current needs of ultra-high-definition video playback. For the most important and time-consuming bitstream analysis and entropy decoding part of the HEVC decoding process, a new hardware architecture strategy is provided, which can effectively improve the HEVC decoding performance. In this paper, the designed data access module, bitstream analysis and entropy decoding unit are simulated and verified. Build an FPGA verification platform, and use the main tier standard test sequence to simulate and verify the designed hardware acceleration architecture. The experimental results show that the hardware architecture of bitstream analysis and entropy decoding designed in this paper can reach the functions and performance indicators specified by the HEVC standard Level-4 main tier, and the bitstream analysis acceleration effect is good. This thesis aims at the current HEVC decoding calculation characteristics, and through the design of hardware architecture verification, it provides new solutions and hardware architecture ideas for subsequent HEVC encoding and decoding performance optimization.

关键词： Analytical models Program processors Video sequences Bit rate Syntactics Prediction algorithms Entropy

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α [email protected] carrier modulated platinum single atoms for high-efficient solar cells

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Applied Surface science 2023年 611卷

作者： Jixin Yao Jie Wang Wen Wang Ying Meng Haibo Wang Shibin Lu Feng Du Li Yang Xueqin Zuo Guang Li Anhui Province Key Laboratory of simulation and design for Electronic information system Universities Joint Key Laboratory of photoelectric detection Science and Technology in Anhui Province Hefei Normal University Hefei 230601 China School of Materials Science and Engineering Anhui Key Laboratory of Information Materials and Devices Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of Education Institute of Physical Science and Information Technology Anhui University Hefei 230601 China Institute of Materials Science and Devices School of Materials Science and Engineering Suzhou University of Science and Technology Suzhou 215011 China

Single-atom electrocatalysts have been proven to be the great promising catalysts for energy-related fields yet their active site structure remains elusive, especially in dye-sensitized solar cell (DSSC). Herein, atomically dispersed Pt is anchored into α [email protected] carrier (Pt/α [email protected] ), which vigorously stimulates the activity of Pt single atoms under the strong metal interaction. As expected, the Pt/α [email protected] as the cathode in DSSC exhibits high power conversion efficiency (PCE) of 9.67%, exceeding Pt electrode (7.61%). X-ray photoelectron spectroscopy combined with density functional theory calculations reveals that the high activity is mainly derived from charge re-distribution of Pt/α [email protected] caused by the interaction between Pt atoms and α-MoC. This interaction not only achieves the optimized adsorption/desorption energy of reactants but also brings synergic advantages to expedite the reaction kinetics of the overall system. This work paves further research prospects for charge re-distribution, stimulating electrocatalysts to effectively enhance their catalytic properties by an atomic-level engineering strategy.

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Design and evaluation of a FPGA-ADC prototype for the PET detector based on LYSO crystals and SiPM arrays

arXiv

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arXiv 2021年

作者： Ma, Cong Dong, Xue Yu, Li Wang, Wubin Zhao, Xiaokun Li, Xing Huang, Zhenqing Wu, Guocheng Lu, Lei Chen, Hansheng The Minfound medical system Co. Ltd. Dongshan Road Shao Xing312000 China Key Laboratory of Far-Shore Wind Power Technology of Zhejiang Province Hangzhou311199 China School of Earth and Space Sciences University of Science and Technology of China Hefei230026 China

the aim of this study is to design and evaluate a simple free running Analog-Digital Converter (ADC) based on the Field Programmable Gate Array (FPGA) device to accomplish the energy and position readout of the silicon photomultiplier (SiPM) array for application as PET scanners. This simple FPGA-ADC based on a carry chain Time-Digital Converter (TDC) implemented on a Kintex-7 FPGA consists of only one off-chip resistor so it has greater advantages in improving system integration and reducing cost than commercial chips. In this paper, a FPGA-ADC based front-end electronics prototype is presented, and both the design principle and implementation considerations are discussed. Experiments were performed using an 8 ×8 (crystal size: 4 ×4 ×15 mm3 ) and a 12 ×12 (crystal size: 2.65 ×2.65 ×15 mm3 ) segmented LYSO crystals coupled with an 8 ×8 SiPM (J-series, from ON Semiconductor) array which is under 22Na point source excitation. Initial test results indicate that the energy resolution of the two detectors after correction is around 13.2% and 13.5 % at 511 keV, and the profiles of the flood histograms show a clear visualization of the discrete scintillator element. All measurements were carried out at room temperature (~25 °C), without additional cooling. Copyright © 2021, The Authors. All rights reserved.

关键词： Medical imaging

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A Comparative Evaluation of AutoEncoder-Based Unsupervised Anomaly Detection Methods Applied on space Payload

A Comparative Evaluation of AutoEncoder-Based Unsupervised A...

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International Conference on Dependable systems and Their Applications (DSA)

作者： Junrong Du Lei Song Taisheng Zheng Lili Guo Chao Ma Key Laboratory of Space Utilization Technology and Engineering Center for Space Utilization Chinese Academy of Sciences University of Chinese Academy of Science Beijing China Key Laboratory of Space Utilization Technology and Engineering Center for Space Utilization Chinese Academy of Sciences Beijing China Beijing key Laboratory of Measurement and Control of Mechanical and Electrical System Beijing Information Science and Technology University Beijing China

ISBN: (数字)9781728160573

ISBN: (纸本)9781728160580

The anomaly detection technology is the basis for ensuring the safe and stable operation of the on-rail payload. The traditional threshold-based anomaly detection method has low accuracy and poor flexibility, and cannot detect abnormalities in real time. In addition, due to the lack of abnormal samples, the distribution of positive and negative samples is extremely imbalanced, which increases the difficulty of abnormal detection. Therefore, this paper proposes an unsupervised learning method based on AutoEncoder and its variants, the Basic AutoEncoder, Deep AutoEncoder and Sparse AutoEncoder are used to verify the algorithm on three public datasets. And using the above three algorithms to carry out the case application on the real load dataset. The experiments show whether in the public dataset or the real data of the payload, the three methods of AutoEncoder have achieved good results, proving the AutoEncoder and its variants have a good application in anomaly detection. At the same time, it is verified that the three algorithms have different effects on different datasets, which proves that the AutoEncoder with different characteristics need to be selected in different scenarios.

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Effect of Annealing on the Transformation Temperatures and Shape Memory Effect of Laser Powder Bed Fusion Niti Alloy

SSRN

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SSRN 2023年

作者： Guo, Yunting Liu, Mengqi Jiang, Chaorui Liu, Ruiyao Zhang, Jundong Liu, Yuting Wang, Zhiying Li, Hang Sha, Pengwei Xin, Renlong Yu, Zhenglei Zhang, Zhihui Xu, Zezhou Ren, Luquan College of Mechanical and Electrical Engineering Northeast Forestry University Harbin150042 China Key Lab of Bionic Engineering Ministry of Education Jilin University Changchun130022 China Weihai institute for Bionic Jilin University Weihai264402 China CAS Key Laboratory of On-orbit Manufacturing Integration for Space Optics System Changchun Institute of Optics Fine Mechanics and Physics Chinese Academy of Sciences Changchun130033 China School of Materials and Metallurgy University of Science and Technology Liaoning Liaoning 114051 China

The appearance of additive manufacturing technology, especially laser powder bed fusion (LPBF), has injected new vitality into the preparation of NiTi alloy. However, the lack of mechanical properties and the decline of the shape memory effect (SME) become the key factors restricting its application. Heat treatment as a means to enhance the performance of metallic materials, especially in the additive manufacturing of metal materials, which can not only eliminate the residual stress generated, but also further improve the performance through the form of precipitation strengthening. In this work, a comprehensive annealing study was carried out on the prepared NiTi alloys to reveal the effect of annealing time (1 h, 3 h and 5 h) and temperature (400 ℃, 500 ℃ and 600 ℃) on the phase transition behavior and the shape memory performance. The mechanism of performance enhancement was analyzed by SEM, EDS, EBSD, and TEM, respectively. The results show that different annealing forms lead to multistep phase transformation behavior, and the 500℃-5h sample with the best SME and mechanical properties. This is due to the formation of nanoscale dispersed precipitates, such as Ni4Ti3 and NiTi2. However, the increase in temperature will lead to the coarse size of the precipitated and sharply weaken the properties of NiTi alloy. Meanwhile, annealing treatment has no significant effect on grain size, texture strength and direction. This research is instructive for the development of the heat treatment process of LPBF-NiTi alloy. © 2023, The Authors. All rights reserved.

关键词： Titanium alloys

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Boron concentration field measurement and mixing analysis in the annular downcomer of reactor pressure vessel 27

Boron concentration field measurement and mixing analysis in...

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27th International Conference on Nuclear Engineering: Nuclear Power Saves the World!, ICONE 2019

作者： Zhang, Qi Tan, Sichao Zhao, Hangbin Wang, Peng Gu, Hanyang Yang, Yunjia School of Nuclear Science and Engineering Shanghai Jiao Tong University Shanghai China Fundamental Science on Nuclear Safety and Simulation Technology Laboratory Harbin Engineer University Harbin Heilongjiang China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China

ISBN: (纸本)9784888983051

In nuclear power plant, the reactor annular downcomer acts as the upstream of the reactor core, and boric distribution inside the downcomer is focused in the ECC situation. The relevant study indicates that the inlet coolant does not flow along annular channel directly, and the current multi primary loops layout makes the fluid mixing of the downcomer far more complex. In this paper, boron transport and mixing phenomenon inside the reactor annular downcomer were analyzed by Laser Induced Fluorescence (LIF) method, a reduziertreduced RPV model was built with transparent material, the boric acid was equivalently simulated by rhodamine B. The single loop and double loops flow mixing tests were respectively performed, the qualitative and quantitative data at cross sections were acquired. For the single loop test, the injected tracer transported along the circumferential position and was constantly diluted by the ambient pure water;meanwhile, a portion of the injection entered the lower space and filled up the annular channel in the same manner. From the time evolution of concentration gradient distribution, the increasement of inlet velocity is favorable to the uniform mixing. For the double loops fluid mixing tests, the tracer solution and pure water were injected into the model simultaneously through two independent entrances. The location of the intersection boundary of the two fluids was affected by the entrance momentum ratio, and the tracer distribution fluctuated remarkably in the lower space of the downcomer. Copyright © 2018-2019 by JSME

关键词： Boric acid

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Thermal analysis of the high sensitivity terahertz detection module under different operating modes of the evaporator

Results in Engineering

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Results in Engineering 2025年

作者： Yantang Hua Chunlong Liu Min Zhang Zhiyong Yang Richa Hu Yan Xiong Zhenyu Lu Liang Guo Changchun Institute of Optics Fine Mechanics and Physics Chinese Academy of Sciences Changchun 130033 China School of Materials Science and Optoelectronic Technology University of Chinese Academy of Sciences Beijing 100049 China CAS Key Laboratory of On-orbit Manufacturing and Integration for Space Optics System Changchun 130033 China Beijing Institute of Control Engineering China Academy of Space Technology Beijing 100190 China

This paper presents a systematic thermal design of the terahertz detection module and analyzes the evaporator's operational modes. A comparative thermal analysis was performed across three modes, with the most extreme condition selected for thermal balance test and a more stable mode designated for default in-orbit operation. simulation results indicate that when evaporators 1 and 2 are operating and evaporator 3 is disconnected (referred to as Mode 3), the internal components of the terahertz detection module experience a significant temperature rise, particularly with the compressor having only a 4.3°C temperature margin. Thermal balance tests confirmed the effectiveness and reliability of the thermal design, with a 2.2°C deviation between the experiment and simulation. In contrast, when evaporators 1 and 3 are operating and evaporator 2 is disconnected (referred to as Mode 2), the internal components remain at relatively low temperatures, especially with the cold finger of the cryostat at only 9.6°C, the lowest among the three modes, making this mode the preferred choice for in-orbit operations. The thermal design and redundant thermal strategies proposed in this study not only ensure the safe operation of the terahertz detection module in orbit but also provide valuable insights and theoretical foundations for the thermal control design of other space exploration systems.

关键词： The high sensitivity terahertz detection module Thermal design Evaporator operating mode Thermal analysis Thermal balance test

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Satellites reveal hot spots of ocean changes in the early 21st century

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science advances 2025年第23期11卷 eads0307页

作者： Zhenghao Li Deyong Sun Shengqiang Wang Yu Huan Hailong Zhang Yijun He State Key Laboratory of Climate System Prediction and Risk Management Nanjing University of Information Science and Technology Nanjing 210044 China. School of Marine Sciences Nanjing University of Information Science and Technology Nanjing 210044 China. Key Laboratory of Space Ocean Remote Sensing and Application Ministry of Natural Resources Beijing 100081 China. School of Marine Technology and Geomatics Jiangsu Ocean University Lian Yungang 222000 China.

Ocean change leaves a potentially important imprint on ocean colorimetry. Here, we present an overview and current evaluation of the global ocean color variability from 1998 to 2022, and satellites observe that 36% of oceans (~122 million square kilometers, derived from valid observations) have experienced changes ( < 0.1). In this context, 25% of the area (formerly blue hue) is turning light blue or green, while the remaining 11% becomes bluer, mainly concentrating in the low-latitude oceans. This study further identifies a "direct" notable impact of both sea surface temperature (SST) and climate on ocean colorimetry tendency and anomaly, especially in the low-latitude oceans. Extreme SST events cause "distinct" ocean colorimetry anomalies, although 94% of cases involve relatively small SST fluctuations. Causal analysis reveals important impacts of climate change on equatorial ocean dynamics, particularly ENSO events. Our findings prove the low-latitude oceans as one of the core changing regions that respond to climate change in the early 21st century.

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