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Impacts of Anthropogenic Discharge on Distribution, Mass Budget, and Long-Term Risk of Total Mercury in Coastal Region: A Case Study of the Jiaozhou Bay, China

SSRN

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SSRN 2023年

作者： Chen, Lufeng Liu, Chang Han, Xiaoxiao Liang, Yong Li, Yanbin State Key Laboratory of Precision Blasting Jianghan University Wuhan430056 China Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances School of Environment and Health Jianghan University Wuhan430056 China State Key Laboratory of Environmental Chemistry and Ecotoxicology Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing100085 China Frontiers Science Center for Deep Ocean Multispheres and Earth System Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education China College of Chemistry and Chemical Engineering Ocean University of China Qingdao266100 China

Mercury (Hg) as a toxic pollutant in marine systems have been paid more attention. The Jiaozhou Bay (JZB) is located at the western coast of the Yellow Sea surrounded by Qingdao city, a developed city in China. More than 10 rivers and several sewage treatment plants carry lots of Hg input it, increasing the environmental risks JZB facing. However, there is still a lack of knowledge on its cycling in the JZB, limiting sound understanding of Hg fate in coastal regions. To address these needs, four cruises were conducted in different seasons, to investigate distribution, controlling factors, and mass budget of total Hg (THg) in the JZB. Higher THg concentrations were determined in seawater and sediment, indicating serious Hg pollution in the JZB. Temperature, salinity in water and enrich factor (EF) in sediment were identified to be factors controlling THg distribution in the JZB. Mass budget of THg showed that river, wastewater input, and atmospheric deposition were dominant source of THg in the JZB. The multiple regression analyses and structural equation model indicated that anthropogenic discharge plays important roles in long-term risk of THg in the JZB. These results suggested that anthropogenic discharge comprehensively affects distribution, mass budget, and long-term risk of THg in coastal systems. The outcomes highlighted that regular investigations of Hg cycling should be conducted to assess Hg pollution in coastal ecosystems. Our study also shed new light on control of long-term risk posed by Hg in marine systems according to investigations of Hg cycling and link between Hg contamination and other pollutant (e.g., nutrient). © 2023, The Authors. All rights reserved.

关键词： Regression analysis

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Fast sheath-driven electrothermal artificial muscles with high power densities

Research Square

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Research Square 2021年

作者： Hu, Xinghao Jia, Jingjing Wang, Yingming Tang, Xintian Fang, Shaoli Wang, Yilun Wang, Jian Baughman, Ray Ding, Jian-Ning The University of Texas Dallas United States Institute of Intelligent Flexible Mechatronics Jiangsu University China State Key Laboratory of Robotics and System Harbin Institute of Technology China Jiangsu University China

Electrothermal carbon nanotube (CNT) yarn muscles can provide large strokes during heating-cooling cycles. However, the slow cooling rate of thermal muscles limit their applications, since large diameter prior-art thermal muscles cannot be rapidly cycled. We here report an ultrafast thermally powered sheath-driven yarn muscle that uses a hybrid CNT sheath and an inexpensive polymer core. Our coiled muscle contracts 14.3% at 1 Hz and 7.3% at 8 Hz in air when powered by a square-wave electrical voltage input. The 70-mm-diameter actuated muscle cools in air to 16℃ from 150℃ within 0.5 s, compared with 6 s for a 65-mm-diameter sheath-run muscle that uses an electrothermally heated CNT core and 9 s for a 78-mm-diameter muscle that uses the sheath material for the entire muscle. An average power density of 12 kW/kg was obtained for a sheath-driven muscle, which is 42 times that for human skeletal muscle. This high performance results since the heating that drives fast actuation cycles is largely restricted to the muscle sheath, and this sheath is in direct contact with ambient temperature air. © 2021, CC BY.

关键词： Carbon nanotubes

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Compressive and Flexural Properties and Damage Modes of Aluminum Foam/Epoxy Resin Interpenetrating Phase Composites Reinforced by Silica Powder

SSRN

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SSRN 2024年

作者： Su, Mingming Zhou, Zhiming Wang, Han Non-destructive Testing Laboratory School of Quality and Technical Supervision Hebei University Baoding071002 China National and Local Joint Engineering Research Center of Metrology Instrument and System Hebei University Baoding071002 China Hebei Key Laboratory of Energy Metering and Safety Testing Technology Hebei University Baoding071002 China State Key Laboratory for Strength and Vibration of Mechanical Structures School of Aerospace Engineering Xi'an Jiaotong University Xi’an710049 China

Interpenetrating phase composites (IPCs) were prepared by connecting open-cell aluminum foam (AF) and epoxy resin (EP) in three-dimensional space. Silica powder was added to epoxy resin to improve the compressive and three-point bending properties of IPCs. In the bending test, acoustic emission (AE) was applied to track the bending deformation of the samples, and k-means clustering algorithm was applied to identify the damage modes. When the content of silica powder was 100 wt.%, the compressive and bending properties of IPCs were the highest. The X-type shear band and EP/AF debonding appeared in compression failures of AF and IPCs, respectively. The AE clustering results showed that under bending load, AF contained plastic deformation of matrix and fracture failure modes, while IPCs included plastic deformation of foam matrix, EP/AF debonding and EP failure modes. © 2024, The Authors. All rights reserved.

关键词： Epoxy resins

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Spike-HAR++: an energy-efficient and lightweight parallel spiking transformer for event-based human action recognition

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Frontiers in Computational Neuroscience 2024年 18卷 1508297页

作者： Lin, Xinxu Liu, Mingxuan Chen, Hong School of Integrated Circuits Tsinghua University Beijing China State Key Laboratory of Integrated Chips and Systems Frontier Institute of Chip and System Fudan University Shanghai China Greater Bay Area National Center of Technology Innovation Research Institute of Tsinghua University in Shenzhen Shenzhen China School of Biomedical Engineering Tsinghua University Beijing China

Event-based cameras are suitable for human action recognition (HAR) by providing movement perception with highly dynamic range, high temporal resolution, high power efficiency and low latency. Spike Neural Networks (SNNs) are naturally suited to deal with the asynchronous and sparse data from the event cameras due to their spike-based event-driven paradigm, with less power consumption compared to artificial neural networks. In this paper, we propose two end-to-end SNNs, namely Spike-HAR and Spike-HAR++, to introduce spiking transformer into event-based HAR. Spike-HAR includes two novel blocks: a spike attention branch, which enables model to focus on regions with high spike rates, reducing the impact of noise to improve the accuracy, and a parallel spike transformer block with simplified spiking self-attention mechanism, increasing computational efficiency. To better extract crucial information from high-level features, we modify the architecture of the spike attention branch and extend it in Spike-HAR to a higher dimension, proposing Spike-HAR++ to further enhance classification performance. Comprehensive experiments were conducted on four HAR datasets: SL-Animals-DVS, N-LSA64, DVS128 Gesture and DailyAction-DVS, to demonstrate the superior performance of our proposed model. Additionally, the proposed Spike-HAR and Spike-HAR++ require only 0.03 and 0.06 mJ, respectively, to process a sequence of event frames, with model sizes of only 0.7 and 1.8 M. This efficiency positions it as a promising new SNN baseline for the HAR community. Code is available at Spike-HAR++. Copyright © 2024 Lin, Liu and Chen.

关键词： Neural networks

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Modeling and Control of General Hydraulic Excavator for Human-in-the-loop Automation

Modeling and Control of General Hydraulic Excavator for Huma...

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International Conference on Tools for Artificial Intelligence (ICTAI)

作者： Guangda Chen Yinghao Gan Jiayi Chen Shuanwu Shi Wei Chen Yingfeng Chen Rong Xiong Changjie Fan Fuxi Robotics in NetEase Hangzhou P.R. China State Key Laboratory of Industrial Control and Technology Zhejiang University Hangzhou P.R. China College of Computer Science and Technology Hangzhou Dianzi University Hangzhou P.R. China Department of Automation Zhejiang University of Technology Hangzhou P.R. China

As labor shortages and safety regulations become more prominent, the need for human-in-the-loop automation of excavators is increasing. To meet this demand, we have developed a comprehensive modeling method for the excavator arm using nonlinear optimization approaches, including a simplified model that maps the task space to the joint space, as well as an equivalent model that maps the joint space to the actuator space. These models were then used to build a feedforward-PID joint velocity controller and a joint trajectory controller combined with position feedback, which forms the core of our proposed semi-automatic control system for the excavator arm. Our deployment scheme is simple and efficient, and has been deployed on two excavators of different makes and sizes. Experiments show that our deployment scheme performs well on both excavators, with an average error of 0.05 rad/s for the velocity controller and less than 5 cm for the trajectory controller. Using our semi-automatic system, we have completed demonstration experiments for precise digging and grading operations. A demonstration video can be found at https://***/N6I0WZGSF68.

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Design of fragment muzzle velocity tester for distributed wireless warhead 2

Design of fragment muzzle velocity tester for distributed wi...

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2021 2nd International Conference on Machine Learning and Computer Application, ICMLCA 2021

作者： Liang, Zhengang Zhao, Meng Tan, Zhaoming Lian, Zhe Wang, Shushan Equipment Engineering College Shenyang Ligong University Hunnan District Liaoning Province Shenyang China China Shipbuilding Industry System Engineering Research Institute Beijing100000 China State Key Laboratory of Explosive Science and Technology Beijing University of Technology Beijing China

ISBN: (纸本)9783800757398

In order to meet the requirement of fragment group velocity measurement in warhead explosive power test, a distributed, multi-channel and wireless communication warhead fragment velocity tester is designed by using data acquisition, Lora protocol wireless communication, data storage and data analysis and processing technologies. The speedometer consists of data acquisition module, wireless data transmission module, wireless data receiving module, data storage module and data processing module. © VDE VERLAG GMBH · Berlin · Offenbach.

关键词： Data handling

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Switchable deep beamformer for high-quality and real-time passive acoustic mapping

arXiv

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arXiv 2024年

作者： Zeng, Yi Li, Jinwei Zhu, Hui Lu, Shukuan Li, Jianfeng Cai, Xiran School of Information Science and Technology ShanghaiTech University Shanghai201210 China Gene Editing Center School of Life Science and Technology ShanghaiTech University Shanghai201210 China State Key Laboratory of Advanced Medical Materials and Devices ShanghaiTech University Shanghai201210 China Key Laboratory of Biomedical Information Engineering of Ministry of Education Department of Biomedical Engineering School of Life Science and Technology Xi’an Jiaotong University Xi’an710049 China Shanghai Engineering Research Center of Intelligent Vision and Imaging ShanghaiTech University Shanghai201210 China Key Laboratory of Biomedical Imaging Science and System Chinese Academy of Sciences Shenzhen518055 China

Passive acoustic mapping (PAM) is a promising tool for monitoring acoustic cavitation activities in the applications of ultrasound therapy. Data-adaptive beamformers for PAM have better image quality compared to the time exposure acoustics (TEA) algorithms. However, the computational cost of data-adaptive beamformers is considerably expensive. In this work, we develop a deep beamformer based on a generative adversarial network, which can switch between different transducer arrays and reconstruct high-quality PAM images directly from radio frequency ultrasound signals with low computational cost. The deep beamformer was trained on the dataset consisting of simulated and experimental cavitation signals of single and multiple microbubble clouds measured by different (linear and phased) arrays covering 1–15 MHz. We compared the performance of the deep beamformer to TEA and three different data-adaptive beamformers using the simulated and experimental test dataset. Compared with TEA, the deep beamformer reduced the energy spread area by 18.9%–65.0% and improved the image signal-to-noise ratio by 9.3–22.9 dB in average for the different arrays in our data. Compared to the data-adaptive beamformers, the deep beamformer reduced the computational cost by three orders of magnitude achieving 10.5 ms image reconstruction speed in our data, while the image quality was as good as that of the data-adaptive beamformers. These results demonstrated the potential of the deep beamformer for high-resolution monitoring of microbubble cavitation activities for ultrasound therapy. Copyright © 2024, The Authors. All rights reserved.

关键词： Cavitation

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Uapgo: Uncertainty-Aware Pose Graph Optimization for Lidar-Based Slam systems

SSRN

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SSRN 2024年

作者： Zhi, Tian Xu, Jie Ma, Yongxin Yu, Wenlu Liu, Shenglan Yuan, Shenghai College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and Astronautics Jiangsu Nanjing210016 China School of Electrical and Electronic Engineering Nanyang Technological University Singapore639798 Singapore State Key Laboratory of Robotics and Systems Harbin Institute of Technology Harbin150001 China School of Mechanical Engineering Shandong University Jinan250061 China

Addressing uncertainty errors, although crucial, may sometimes be deprioritized in the optimization process ofLiDAR-based SLAM systems due to the inherent complexity of the task. The practice of applying uniform weights, which simplifies the uncertainty management, when incorporating factors can inadvertently degrade the pose graph optimization, particularly within complex environments. In response to this, we propose anuncertainty-aware pose graph optimization technique, along with an innovative keyframe selection strategy. We develop a model for estimating the covariance of relative pose transformations, utilizing frontend odometry output and the Huber robust kernel function. This model assigns weights based on the uncertainty error of pose transformations. Upon detection of a loop closure, the system optimizes keyframe poses, effectively reducing cumulative error. Our keyframe selection strategy takes into account the maximum eigenvalue of the translational component of pose covariance as an uncertainty measure. If this value surpasses a certain threshold, the pose is selected as a keyframe, thereby enhancing data precision and computational efficiency, and subsequently improving the SLAM system’s ability to handle uncertainty. Ablation studies validate our approach, demonstrating its effectiveness in enhancing performance, especially in complex environments and conditions of data degradation. Wealso provide the associated open-source code for further research. © 2024, The Authors. All rights reserved.

关键词： Eigenvalues and eigenfunctions

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Pre-configuration Method and Scheduling Strategy of Distribution Network Mobile Energy Storage Vehicle Considering Intermittent Load of Rural Network

Pre-configuration Method and Scheduling Strategy of Distribu...

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Electronics and Devices, Computational Science (ICEDCS), International Conference on

作者： Xiaoming Lu Yiwen Yao Yechen Xin Dingheng Wang Xinhong Wang Xin Xu Hao Li Economic and Technological Research Institute State Grid Jilin Electric Power Co. Ltd Changchun China Key Laboratory of Modern Power System Simulation and Control & Renewable Energy Technology Ministry of Education Northeast Electric Power University Jilin China State Grid Jilin Electric Power Co. Ltd Changchun China

ISBN: (数字)9798331527624

ISBN: (纸本)9798331527631

Aiming at the problem of heavy overload in the distribution station area during the peak period of energy consumption caused by intermittent loads such as agricultural motor wells, the mobile energy storage technology is considered to meet the agricultural power demand, and a two-stage mobile energy storage vehicle pre configuration and dynamic adjustment strategy of "Rural busy power energization" and "rural idle distributed energy storage" is proposed, taking into account the guarantee of load power demand and the efficiency and economy of energy storage. Firstly, the mathematical model of agricultural motor well load considering the time shift characteristics and the mobile energy storage vehicle model considering the power supply time constraint are established; Secondly, a multi-stage mobile energy storage configuration and scheduling strategy is established. In the Rural busy power generation stage, the mobile energy storage vehicle capacity is configured with the minimum daily power supply cost as the goal, and the power supply path is optimized with the highest charge state consistency at the completion of power supply as the goal; At the stage of distributed energy storage in rural slack, the collaborative optimization of mobile energy storage vehicles participating in multi scenario power services is carried out with the goal of maximizing the annual net income. Finally, the proposed two-stage strategy has certain economic benefits under the premise of meeting the power demand of the load, which is verified by combining the power consumption data of wells in Jilin Province and IEEE 33 bus system simulation.

关键词： Energy consumption Power demand Costs Distribution networks Motors Time factors Vehicle dynamics Optimization Energy storage Load modeling

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Simulation Analysis of the Influence of Harmonics Current on the Winding Temperature Distribution of Converter Transformer 6

Simulation Analysis of the Influence of Harmonics Current on...

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6th Asia Conference on Power and Electrical Engineering, ACPEE 2021

作者： Zhang, Jie Cheng, Lin Wen, Hao Liu, Cong Hao, Jian Li, Zhiwei Nari Group Corporation/State Grid Electric Power Research Institute Nanjing China Chongqing University State Key Laboratory of Power Transmission Equipment System Security and New Technology Chongqing China Baoding Tianwei Baobian Electrical Limited Company Baoding China

ISBN: (纸本)9781728191591

The converter transformer is directly connected to the main non sinusoidal power receiving equipment of the power network, the converter valve, which has a large harmonic content. The temperature rise is an important index to reflect the internal state and safe transmission capacity of converter transformer, so the influence of harmonics on the temperature rise of converter transformer winding is worthy of attention. Taking the actual converter transformer as an example, the magnetic field simulation model and heat flow simulation model of the converter transformer are established, and the variation of winding loss and winding temperature distribution under different harmonic content and harmonic frequency are simulated and studied. It is found that when the harmonic content increases, the harmonic current of the winding increases, so the resistance loss of the winding increases, and the hot spot temperature rise of the winding increases in a power function with the harmonic content;when the harmonic content increases, the equivalent resistance of the winding increases, so the resistance loss of the winding increases, and the hot spot temperature rise of the winding increases in an exponential function with the harmonic frequency. Finally, the quantitative relationship of winding temperature rise under different harmonic content and harmonic frequency is obtained. © 2021 IEEE.

关键词： Temperature distribution

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