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High-Order Accurate Entropy Stable Schemes for Relativistic Hydrodynamics with General Synge-Type Equation of State

JOURNAL OF SCIENTIFIC COMPUTING 2024年第2期98卷 43-43页

作者： Xu, Linfeng Ding, Shengrong Wu, Kailiang Southern Univ Sci & Technol Dept Math Shenzhen 518055 Peoples R China Southern Univ Sci & Technol SUSTech Int Ctr Math Shenzhen 518055 Peoples R China Southern Univ Sci & Technol SUSTech Int Ctr Math Natl Ctr Appl Math Shenzhen NCAMS Dept Math Shenzhen 518055 Peoples R China Natl Ctr Appl Math Shenzhen NCAMS Shenzhen 518055 Peoples R China

All the existing entropy stable (ES) schemes for relativistic hydrodynamics (RHD) in the literature were restricted to the ideal equation of state (EOS), which however is often a poor approximation for most relativistic flows due to its inconsistency with the relativistic kinetic theory. This paper develops high-order ES finite difference schemes for RHD with general Synge-type EOS, which encompasses a range of special EOSs. We first establish an entropy pair for the RHD equations with general Synge-type EOS in any space dimensions. We rigorously prove that the found entropy function is strictly convex and derive the associated entropy variables, laying the foundation for designing entropy conservative (EC) and ES schemes. Due to relativistic effects, one cannot explicitly express primitive variables, fluxes, and entropy variables in terms of conservative variables. Consequently, this highly complicates the analysis of the entropy structure of the RHD equations, the investigation of entropy convexity, and the construction of EC numerical fluxes. By using a suitable set of parameter variables, we construct novel two-point EC fluxes in a unified form for general Synge-type EOS. We obtain high-order EC schemes through linear combinations of the two-point EC fluxes. Arbitrarily high-order accurate ES schemes are achieved by incorporating dissipation terms into the EC schemes, based on (weighted) essentially non-oscillatory reconstructions. Additionally, we derive the general dissipation matrix for general Synge-type EOS based on the scaled eigenvectors of the RHD system. We also define a suitable average of the dissipation matrix at the cell interfaces to ensure that the resulting ES schemes can resolve stationary contact discontinuities accurately. Several numerical examples are provided to validate the accuracy and effectiveness of our schemes for RHD with four special EOSs.

关键词： Entropy stable scheme Entropy conservative scheme Relativistic hydrodynamics Equation of state Dissipation matrix

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An Occlusion-Free Intraoperative Active Navigation System for Orthopedic Surgery

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IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT 2024年 73卷 1页

作者： Meng, Yiyang Geng, Pengxiu Luo, Mengde Qin, Yanding Han, Jianda Nankai Univ Coll Artificial Intelligence Tianjin 300350 Peoples R China Nankai Univ Shenzhen Res Inst Shenzhen 518083 Peoples R China

Intraoperative optical tracking system (OTS) suffers from the visual occlusion problem when an obstacle blocks the visual cone (VC) of the OTS. In this article, angle and distance margins are proposed to quantify the degree of danger of an obstacle based on its spatial relationship to the VCs of the OTS. Based on this mathematical modeling, an active navigation system (ANS) is proposed, where the navigation robot is used to adjust the pose of the OTS before occlusion occurs. Circular and translational trajectories are proposed as basic adjusting trajectories for the OTS. A dual-step optimization is then established to find the optimal observation pose of the OTS and plan an occlusion-free adjusting trajectory for the navigation robot. Finally, simulations and experiments are conducted to validate the effectiveness of the proposed method. The results demonstrate that the proposed method effectively keeps the VCs of the OTS away from the moving path of the obstacle, and thus maintaining consistent navigation. This active navigation method is promising for the safe operations of surgical systems employing optical navigation.

关键词： Active navigation occlusion avoidance optical tracking system (OTS) robotic surgery surgical navigation

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Exploring and Exploiting High-Order Spatial-Temporal Dynamics for Long-Term Frame Prediction

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO technology 2024年第3期34卷 1841-1856页

作者： Dai, Kuai Li, Xutao Ye, Yunming Wang, Yaowei Feng, Shanshan Xian, Di Harbin Inst Technol Dept Comp Sci Shenzhen 518055 Peoples R China Harbin Inst Technol Dept Comp Sci Shenzhen 518055 Peoples R China Peng Cheng Lab Shenzhen 518000 Peoples R China Wecar Technol Co Ltd Shenzhen 518057 Peoples R China China Meteorol Adm Natl Satellite Meteorol Ctr Beijing 100081 Peoples R China

Long-term spatial-temporal frame prediction focuses on predicting future image frames precisely, which has numerous applications in real-world scenarios. Existing deep learning prediction models mainly rely on advanced neural network architectures to model complicated spatial-temporal features, which make few efforts to explore high-order correlations to better capture long-term dynamics. Their prediction on long-term frames suffers from inaccurate visual and motion detail issue. In this article, we propose a high-order prediction model for long-term frame prediction, which improves the appearance and motion details by designing special high-order correlation modules in two aspects. First, to enhance the appearance details of predicted frames, we propose a high-order appearance encoder module, where high-order appearance features can be effectively captured with a carefully designed Non-local ConvLSTM. Second, to guarantee the motion accuracy of predicted sequences, we carefully design a high-order motion encoder module, which can accurately capture and preserve the high-order motion patterns with adaptive motion extractors and progressive memory banks, respectively. Comprehensive experiments are conducted on six challenging datasets from real-world scenarios, which demonstrate the effectiveness and superiority of our proposed method over state-of-the-art methods.

关键词： Long-term spatial-temporal frame prediction high-order appearance features high-order motion patterns

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The Impacts of Regime Shift in Summer Arctic Oscillation on Precipitation in East Asia

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ATMOSPHERE 2024年第3期15卷 283页

作者： Zou, Xuxin Yan, Li Xu, Jianjun Zheng, Shaojun Guangdong Ocean Univ South China Sea Inst Marine Meteorol Coll Ocean & Meteorol Lab Coastal Ocean Variat & Disaster Predict Zhanjiang 524088 Peoples R China Guangdong Ocean Univ Shenzhen Inst Shenzhen 518120 Peoples R China

Using multiple observational and reanalysis data, this paper investigates the impact of the interdecadal shift in summer Arctic Oscillation (AO) on precipitation in East Asia, by removing ENSO influences. The results indicate that the lower-layer activity center of summer AO in Atlantic shifted eastward after the mid-1980s. This regime shift of summer AO has a significant impact on precipitation in East Asia. Before the mid-1980s, the key regions in which precipitation was affected by AO in East Asia were northern East Asia and Northeastern China and adjacent regions. After the mid-1980s, the key regions in which precipitation was affected by AO in East Asia were central Inner Mongolia and Southern China. The mechanism of precipitation changes can be attributed to changes in atmospheric circulation and water vapor transport related to AO changes. After the mid-1980s, the influence of AO on geopotential height over northern East Asia weakened;meanwhile, the impact of AO on geopotential height over China increased. Consistent with the changes in atmospheric circulation, water vapor transport in East Asia also underwent interdecadal changes before and after the mid-1980s. The differences in atmospheric circulation and water vapor transport in East Asia can be traced back to the North Atlantic. Before the mid-1980s, wave activity flux related to summer AO tended to propagate in high latitudes and subtropics;after the mid-1980s, the wave activity flux changed in its subtropical path and propagated eastward from the North Atlantic through the Middle East to China, significantly affecting the summer precipitation in China.

关键词： Arctic Oscillation East Asia summer precipitation regime shift water vapor transport wave activity flux

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Toward Large-Scale Palmprint Image Analysis by a Rich Orientation Code

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IEEE TRANSACTIONS ON SYSTEMS MAN CYBERNETICS-SYSTEMS 2024年第7期54卷 4113-4125页

作者： Fan, Dandan Liang, Xu Jia, Wei Zhang, David Chinese Univ Hong Kong Shenzhen Sch Data Sci Shenzhen 518172 Peoples R China Northwestern Polytech Univ Sch Software Xian 710072 Peoples R China Hefei Univ Technol Sch Comp & Informat Hefei 230002 Peoples R China Chinese Univ Hong Kong Sch Data Sci Shenzhen 518172 Peoples R China Chinese Univ Hong Kong Shenzhen Shenzhen Inst Artificial Intelligence Robot Soc Shenzhen Peoples R China

Palmprint recognition has gained considerable attention in recent years, accompanied by significant progress. However, large-scale palmprint recognition, which holds great potential for extensive civilian applications like university access control, remains underexplored. In this work, we propose the CUHK-T dataset, the largest palmprint dataset to date, containing over 10k individuals' palmprints. As the data volume expands, the heightened complexity, such as similar principal lines from different palms, necessitates a recognition method capable of extracting more discriminative features. Motivated by the rich palm lines distributed in palmprint, including not only nonintersecting, but also intersecting line segments, we model intersecting lines, investigate their properties, and propose a novel and explainable palmprint recognition method. The model treats the nonintersecting line segment as a special case, allowing for the extraction of orientation information from both types of line segments. In addition to the rich orientation information of the intersecting lines, the extracted feature accounts for the relative width of these lines. These advancements enable the extracted rich orientation code to be more discriminative and representative for palmprint. We then present a bitwise similarity measurement for efficiently and effectively comparing two rich orientation codes. Our extensive experiments and evaluations with popular palmprint recognition algorithms demonstrate the effectiveness and superior performance of our method on the large-scale dataset. These results also serve as a foundational baseline, facilitating the advancement of further research in the domain of large-scale palmprint recognition.

关键词： Palmprint recognition Feature extraction Codes Data mining Databases Lighting Light sources Biometrics large-scale palmprint recognition orientation features palm lines

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Preparation and Properties of Atomic-Oxygen Resistant Polyimide Films Based on Multi-Ring Fluoro-Containing Dianhydride and Phosphorus-Containing Diamine

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POLYMERS 2024年第3期16卷 343页

作者： Wang, Zhenzhong Ren, Xi Zhang, Yan Yang, Changxu Han, Shujun Qi, Yuexin Liu, Jingang China Univ Geosci Minist Educ Geol Carbon Storage & Low Carbon Utili Sch Mat Sci & Technol Engn Res Ctr Beijing 100083 Peoples R China

Colorless and transparent polyimide (CPI) films with good atomic oxygen (AO) resistance and high thermal endurance are highly required in low earth orbit (LEO) space exploration. Conventional CPI films based on fluoro-containing 4,4 '-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) have been widely used in space applications. However, the AO erosion yields and glass transition temperatures (T-g) of the 6FDA-based CPI films have to be modified in order to meet the severe serving environments. In the current work, novel CPI films based on a multi-ring fluoro-containing 9,9-bis(trifluoromethyl)xanthene-2,3,6,7-tetracarboxylicdianhydride (6FCDA) monomer were developed. In order to enhance the AO resistance of the derived CPI film, a phosphorus-containing aromatic diamine, 2,5-bis[(4-aminophenoxy)phenyl]diphenylphosphine oxide (BADPO) was used to polymerize with the dianhydride to create the organo-soluble resin. Then, two phosphorus-containing CPI films (PPI), including PPI-1 (6FDA-BADPO) and PPI-2 (6FCDA-BADPO) were prepared by thermally curing of the PPI solutions at elevated temperatures. The PPI films maintained good optical transparency with transmittance values over 80% at a wavelength of 450 nm. PPI-2 exhibited a T-g value of 311.0 degrees C by differential scanning calorimetry (DSC) measurement, which was 46.7 degrees C higher than that of the PPI-1 counterpart (T-g = 264.3 degrees C). In addition, the PPI-2 film showed a coefficient of linear thermal expansion (CTE) value of 41.7 x 10(-6)/K in the range of 50 similar to 250 degrees C, which was apparently lower than that of the PPI-1 sample (CTE = 49.2 x 10(-6)/K). Lastly, both of the two PPI films exhibited good AO resistance with the erosion yields (E-y) of 6.99 x 10(-25) cm(3)/atom for PPI-1 and 7.23 x 10(-25) cm(3)/atom for PPI-2 at an exposure flux of 5.0 x 10(20) atoms/cm(2). The E-y values of the current PPI films were obviously lower than that of the standard polyimide (PI) film based on pyromelli

关键词： fluoro-containing polyimide atomic oxygen low earth orbit optical properties thermal properties

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Learning to Predict Diverse Stable Placements for Extrinsic Manipulation on a Support Plane

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IEEE TRANSACTIONS ON COGNITIVE AND DEVELOPMENTAL SYSTEMS 2024年第3期16卷 1095-1107页

作者： Xu, Peng Chen, Zhiyuan Wang, Jiankun Meng, Max Q. -H. Chinese Univ Hong Kong Dept Elect Engn Hong Kong Peoples R China Southern Univ Sci & Technol Shenzhen Key Lab Robot Percept & Intelligence Shenzhen 518055 Peoples R China Southern Univ Sci & Technol Dept Elect & Elect Engn Shenzhen 518055 Peoples R China Southern Univ Sci & Technol Jiaxing Res Inst Jiaxing 314019 Peoples R China Univ Alberta Dept Elect & Comp Engn Edmonton AB T6G 2R3 Canada

Extrinsic manipulation, a technique that enables robots to leverage extrinsic resources for object manipulation, presents practical yet challenging scenarios. Particularly in the context of extrinsic manipulation on a supporting plane, regrasping becomes essential for achieving the desired final object poses. This process involves sequential operation steps and stable placements of objects, which provide grasp space for the robot. To address this challenge, we focus on predicting diverse placements of objects on the plane using deep neural networks. A framework that comprises orientation generation, placement refinement, and placement discrimination stages is proposed, leveraging point clouds to obtain precise and diverse stable placements. To facilitate training, a large-scale dataset is constructed, encompassing stable object placements and contact information between objects. Through extensive experiments, our approach is demonstrated to outperform the start-of-the-art, achieving an accuracy rate of 90.4% and a diversity rate of 81.3% in predicted placements. Furthermore, we validate the effectiveness of our approach through real-robot experiments, demonstrating its capability to compute sequential pick-and-place steps based on the predicted placements for regrasping objects to goal poses that are not readily attainable within a single step.

关键词： Robots Point cloud compression Task analysis Predictive models Neural networks Computational modeling Stability analysis Deep learning extrinsic manipulation regrasping

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A Phased-Array Transceiver With 2-Dimension Continuously Auto Link-Tracking Operation and Time Division Modulator

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IEEE JOURNAL OF SOLID-STATE CIRCUITS 2024年第8期59卷 2390-2406页

作者： Luo, Xun Yang, Bingzheng Deng, Zhixian Chen, Wen Shu, Yiyang Zhou, Jie Univ Elect Sci & Technol China UESTC Shenzhen Inst Adv Study Shenzhen 518110 Peoples R China UESTC Ctr Adv Semicond & Integrated Microsyst Chengdu 611731 Peoples R China

This work presents an eight-element 23-40 GHz continuously auto link-tracking phased-array transceiver (TRX) with a time division modulator in a conventional 40-nm CMOS technology. Such a TRX array can support fast auto-beam-steering in both receiver (RX) and transmitter (TX) arrays. The link-tracking loop is introduced to generate the phase and amplitude control codes of the RX array, which can automatically steer the RX beam to the unknown target direction to establish the RX link. After the RX link is located, the link-tracking loop provides a phase control code to steer the TX beam toward the target. Meanwhile, the time division modulator consists of four digital power amplifiers (DPAs), a quadrature signal generator, and a sign-map circuit. The time division modulator can not only tune the LO power for RX gain flatness improvement but also provide a baseband-to-RF direct conversion in TX mode. The measured link-tracking time and peak TX system efficiency are 7 mu s and 25.3%, respectively, while the proposed TRX array can support 4.8 Gb/s 64-QAM and 8 Gb/s 16-QAM transmission.

关键词： Phased arrays Codes Phase modulation Wireless communication Wideband Transceivers Target tracking Digital power amplifier (DPA) link-tracking millimeter-wave (mm-wave) phased-array time-division modulator transceiver (TRX) wideband

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Synergistic effects of adsorption and chemical reduction towards the effective Cr(VI) removal in the presence of the sulfur-doped biochar material

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ENVIRONMENTAL science AND POLLUTION RESEARCH 2024年第6期31卷 8538-8551页

作者： Ma, Rui Xu, Xiangning Zhang, Yichu Zhang, Dandan Xiang, Guoping Chen, Yongjun Qian, Jin Yi, Shouliang Northwestern Polytech Univ Sch Chem & Chem Engn Res & Dev Inst Shenzhen Xian Peoples R China 2nd Geol Brigade Sichuan Chengdu Peoples R China US DOE Natl Energy Technol Lab Pittsburgh PA 15236 USA

In this study, the anaerobic sludge withdrawn from thickener in a sewage treatment plant served as the precursor for sludge-based biochar fabrication, which was further modified via sulfur (S) heteroatom doping (i.e., S-BC). The S atom doping resulted in the adjustment of the physicochemical properties towards the carbon material, endowment of abundant functional groups on biochar surface, and increasing the binding sites between biochar and Cr(VI). Compared to the primary biochar (i.e., biochar without heteroatomic doping, named BC), S-BC exhibited a rough surface and possessed remarkable advantages in ash content, specific surface area, and pore volume. The existence of graphene carbon crystal structure for S-BC was confirmed through S-BC by XRD and FTIR analysis. The studies of adsorption kinetics and isotherms showed that pseudo-second-order kinetics and the Langmuir model more fitted the Cr(VI) removal behavior in the presence of S-BC. Therefore, the chemisorption and monolayer adsorption were the primary mechanisms involved in the Cr(VI) removal process. Additionally, XPS analysis results illustrated the aqueous Cr(VI) was efficiently eliminated through the synergistic effect of chemisorption and reduction to Cr(III) in the presence of S-BC. Moreover, S-BC could still achieve the Cr(VI) eliminating efficiency of 85.31% undergoing five cycles with unchanged functional group and crystal structure via FTIR and XRD analysis. Thus, the results of this study may shed light on a new approach for simultaneous economical sludge disposal and the sustainable remediation of the Cr(VI)-contaminated wastewater.

关键词： Waste-activated sludge (WAS) treatment and disposal Biochar Sulfur (S) doping Adsorption and reduction Cr(VI)

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Flexible LC Sensor Array for Wireless Multizone Pressure Monitoring

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IEEE SENSORS JOURNAL 2024年第3期24卷 2628-2636页

作者： Zhang, Yunfan Tang, Wuyang Chen, Hongbin Li, Hui Xue, Zifan Shen, Shengnan Wuhan Univ Inst Technol Sci Hubei Prov Engn Res Ctr Integrated Circuit Packagi Sch Power & Mech Engn Wuhan 430072 Peoples R China Wuhan Univ Shenzhen Res Inst Shenzhen 518057 Peoples R China Wuhan Univ Pulm & Crit Care Med Renmin Hosp Wuhan 430060 Peoples R China

Flexible pressure sensors have shown great potential in medical field due to the advantages of excellent flexibility and comfortable wearing. In this article, a flexible inductive-capacitive (LC) sensor array is proposed for wireless multizone pressure monitoring. It consists of three pressure-sensitive LC sensors that operate in nonoverlapping frequency channels. Nano-Ag particles are inkjet printed on polyimide (PI) substrate to fabricate the LC circuits. A thin layer of polydimethylsiloxane (PDMS) is spin-coated onto the circuit, serving as both an electrical insulating layer to prevent shorting out and a deformable dielectric layer between the two capacitor plates when the circuit is folded. Benefiting from the folding design, the PI substrate acts as an external package that provides optimal protection for the entire device. Simulations and experiments are conducted to evaluate the performance in wireless multizone pressure monitoring using the LC sensor array. The results indicate a sensitivity of up to 0.235 MHz/kPa in the range of 0-100 kPa, as well as stability with a bias less than 0.15 MHz over 300 pressure cycles. Furthermore, the sensor array is successfully applied to detect finger flexion, smile, and swallow, showing a promising potential in human health monitoring.

关键词： Sensors Sensor arrays Capacitors Monitoring Capacitive sensors Inductors Dielectrics Flexible sensor inductive-capacitive (LC) circuit multizone pressure monitoring

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