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Experimental Study on Geometry Characteristics of Turbulent Premixed Flames for Natural Gas/Air Mixtures

Journal of Thermal Science 2025年第1期34卷 268-282页

作者： ZHENG Weilin WANG Qijiao XIAO Huahua CHEN Xiaoxiao XIE Fan ZENG Wen Liaoning Key Lab of Advanced Test Technology for Aerospace Propulsion System Shenyang Aerospace UniversityShenyang 110136China State Key Laboratory of Fire Science University of science and Technology of ChinaHefei 230027China AVIC Shenyang Aircraft Design and Research Institute Shenyang 110035China

In this study,focusing on the geometry characteristics of spherical expanding flame,the turbulent premixed flames of natural gas/air mixtures were investigated in a fan-stirred turbulent *** effects of initial temperature(T=300-400 K),initial pressure(P=0.1-0.3 MPa),turbulence intensity(u'=1.0-2.7 m/s),oxygen volumetric percentage(φ(O_(2))=15%-21%)and carbon dioxide volumetric percentage(φ(CO_(2))=0-20%)were delved *** flame profile under the Cartesian coordinate system was derived from the schlieren images taken by the high-speed ***,from both macroscopic and microscopic perspectives,the influence of experimental conditions on the flame geometry characteristics was explored through flame front extraction,wavelet decomposition and network *** results demonstrate that for significant flame wrinkling,changes in species concentrations and turbulence intensity have more pronounced effects on the flame wrinkling *** wrinkling of the flame front maintains a certain degree of similarity,as evidenced by the locally concentrated distribution of the angles of the maximum fluctuation *** disturbance energy under large-scale(D6-D8)disturbances exhibits relatively high values with a similar trend,exerting a significant impact on the geometry characteristics of the flame *** peaks of correlation degree are scattered either with the decomposition scale or the development of flame radius,indicating no linear correlation between different detail ***,the probability distribution of node degrees in key wrinkled regions exhibits different trends with that of large-scale wrinkling and disturbance energy,especially with changes in initial *** occurs because the number of key wrinkles varies based on the perturbation's strength or the region's ***,an increase in the fluctuation frequency of the flame's local radius may not necessarily lead to an increase in the number of key folded regions.

关键词： geometry characteristics large-scale wrinkling wavelet decomposition network topology fan-stirred turbulent combustor

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Design memristor-based computing-in-memory for AI accelerators considering the interplay between devices, circuits, and system

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Science China(Information Sciences) 2023年第8期66卷 243-253页

作者： Junjie AN Linfang WANG Wang YE Weizeng LI Hanghang GAO Zhi LI Zhidao ZHOU Jinghui TIAN Jianfeng GAO Chunmeng DOU Qi LIU School of Microelectronics University of Science and Technology of China State key Lab of Fabrication Technologies for Integrated Circuits Institute of MicroelectronicsChinese Academy of Sciences School of Microelectronics University of Chinese Academy of Sciences Frontier Institute of Chip and System State Key Laboratory of ASIC and System Fudan University

Recent advances in developing beyond von Neumann architectures have moved the memristive devices to the forefront as one of the key enablers to realizing memristive computing-in-memory(m CIM)structures, which shows a great promise to boost the energy-efficiency and the performance of artificial intelligence(AI) chips. In this study, by considering the interactions between devices, circuits, and systems in the m CIM design, we propose several cross-layer design techniques, including(1) the BL-SL interactive forming protection(BSIFP) circuit that can reduce the voltage drop on the selected transistor, suppress the current overshoot by 65.96%, and improve the bit-cell density by more than 10.19%,(2) the clamping transistor trimming scheme(CTTS) to prevent the multiply-and-accumulate(MAC) signal margin degradation from chip-to-chip resistance variations, and(3) dynamic input-parallelism and output-precision(DIPOP) that can reduce the energy cost by 22.92% in a typical inference task with negligible accuracy loss. The results demonstrate the significant role of the cross-layer-interactive approach and provide a preliminary guideline for highly-efficient m CIM design.

关键词： memristor resistive memory computing-in-memory artificial intelligence cross-layer co-design

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Construction of mesoporous silica-implanted tungsten oxides for selective acetone gas sensing

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Chinese Chemical Letters 2024年第11期35卷 492-498页

作者： Jichun Li Zhengren Wang Yu Deng Hongxiu Yu Yonghui Deng Xiaowei Cheng Kaiping Yuan Department of Chemistry Shanghai Stomatological Hospital&School of StomatologyState Key Laboratory of Molecular Engineering of PolymersShanghai Key Laboratory of Molecular Catalysis and Innovative MaterialsiCHEMFudan UniversityShanghai 200433China Frontier Institute of Chip and System State Key Laboratory of ASIC and SystemFudan UniversityShanghai 200433China State Key Lab of Transducer Technology Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai 200050China

As a key biomarker for noninvasive diagnosis of diabetes,the selective detection of trace acetone in exhaled gas using a portable and low-cost device remains a great *** metal oxide(SMO)based gas sensors have drawn signification attention due to their potential in miniaturization,user-friendliness,high cost-effectiveness and selective real-time detection for noninvasive clinical ***,we propose a one-pot solvent evaporation induced tricomponent co-assembly strategy to design a novel ordered mesoporous SMO of silica-implanted WO_(3)(Si O_(2)/WO_(3))as sensing materials for trace acetone *** controlled co-assembly of silicon and tungsten precursors and amphiphilic diblock copolymer poly(ethylene oxide)-block-polystyrene(PEO-b-PS),and the subsequent thermal treatment enable the local lattice disorder of WO_(3)induced by the amorphous silica and the formation of ordered mesoporous Si O_(2)/WO_(3)hybrid walls with a unique metastableε-phase WO_(3)*** obtained mesoporous SiO_(2)/WO_(3)composites possess highly crystalline framework with large uniform pore size(12.0-13.3 nm),high surface area(99-113 m^(2)/g)and pore volume(0.17-0.23 cm^(3)/g).Typically,the asfabricated gas sensor based on mesoporous 2.5%Si O_(2)/WO_(3)exhibits rapid response/recovery rate(5/17 s),superior sensitivity(R_(air)/R_(gas)=105 for 50 ppm acetone),as well as high selectivity towards *** limit of detection is as low as 0.25 ppm,which is considerably lower than the thresh value of acetone concentration(>1.1 ppm)in the exhaled breath of diabetic patients,demonstrating its great prospect in real-time monitoring in diabetes ***,the mesoporous 2.5%Si O_(2)/WO_(3)sensor is integrated into a wireless sensing module connected to a smart phone,providing a convenient real-time detection of acetone.

关键词： Mesoporous materials ε-Tungsten oxide Silica-implanted Acetone sensing Real-time detection

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A Variable Frequency Voltage Injection Method for Modular Multilevel Converter in Variable Speed Driver 4th

A Variable Frequency Voltage Injection Method for Modular Mu...

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4th International Symposium on Insulation and Discharge Computation for Power Equipment, IDCOMPU 2023

作者： Jia, Guanlong Li, Mingshuo Feng, Dawei Shi, Binhao Liu, Xiaoming Huang, Jun State Key Lab of Reliability and Intelligence of Electrical Equipment HeBei University of Technology Tianjin China

ISBN: (纸本)9789819974122

Modular Multilevel Converter (MMC) is a common multilevel topology for medium voltage motor drives. However, the voltage fluctuation of the sub-module (SM) capacitor is the main obstacle when motor runs at low speed. A variable frequency voltage injection method is recommended in this paper, in which the frequency of the injection voltage changes synchronously with the speed (output frequency) and is permanently guaranteed to be K times of the frequency. The optimal voltage suppression can be achieved at low frequency operation and overmodulation can be effectively avoided. Finally, the availability of the recommended variable frequency voltage injection method is checked with simulation and experimental results. © Beijing Paike Culture Commu. Co., Ltd 2024.

关键词： Variable speed drives

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FreeLong: Training-Free Long Video Generation with SpectralBlend Temporal Attention 38

FreeLong: Training-Free Long Video Generation with SpectralB...

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38th Conference on Neural Information Processing systems, NeurIPS 2024

作者： Lu, Yu Liang, Yuanzhi Zhu, Linchao Yang, Yi The State Key Lab of Brain-Machine Intelligence Zhejiang University China University of Technology Sydney Australia

Video diffusion models have made substantial progress in various video generation applications. However, training models for long video generation tasks require significant computational and data resources, posing a challenge to developing long video diffusion models. This paper investigates a straightforward and training-free approach to extend an existing short video diffusion model (e.g., pre-trained on 16-frame videos) for consistent long video generation (e.g., 128 frames). Our preliminary observation has found that directly applying the short video diffusion model to generate long videos can lead to severe video quality degradation. Further investigation reveals that this degradation is primarily due to the distortion of high-frequency components in long videos, characterized by a decrease in spatial high-frequency components and an increase in temporal high-frequency components. Motivated by this, we propose a novel solution named FreeLong to balance the frequency distribution of long video features during the denoising process. FreeLong blends the low-frequency components of global video features, which encapsulate the entire video sequence, with the high-frequency components of local video features that focus on shorter subsequences of frames. This approach maintains global consistency while incorporating diverse and high-quality spatiotemporal details from local videos, enhancing both the consistency and fidelity of long video generation. We evaluated FreeLong on multiple base video diffusion models and observed significant improvements. Additionally, our method supports coherent multi-prompt generation, ensuring both visual coherence and seamless transitions between scenes. Our project page is at: https://***/freelong. © 2024 Neural information processing systems foundation. All rights reserved.

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Design of Doppler Resilient Sequences and Receiving Filters Against Interrupted-Sampling Repeater Jamming for Simultaneously Polarimetric Radars

IEEE Transactions on Radar Systems

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IEEE Transactions on Radar systems 2024年 2卷 661-676页

作者： Li, Nanjun Wang, Fulai Pang, Chen Li, Yongzhen National University of Defense Technology State Key Lab. of Complex Electromagnetic Environment Effects on Electronics and Information System Changsha410073 China

Aimed to enhance the robustness of simultaneously polarimetric radar (SPR) systems against interrupted-sampling repeater jamming (ISRJ) attacks by polarization and waveform diversity techniques, this article focuses on the joint design of unimodular sequences and receiving filters for jamming suppression. Specifically, we first develop a dynamic signal processing framework for target polarization scattering matrix (PSM) estimation based on their statistical properties and orthogonal conditions between receiving filters and ISRJ signals. Then, the weighted sum of integrated sidelobe levels (ISLs) of auto- and cross-ambiguity functions and signal-to-noise ratio losses (SNRLs) is minimized with unimodular and energy constraints to mitigate ISRJ in SPR systems considering both single pulse and multipulse. To handle the resulting NP-hard design problems, an iterative optimization method capitalizing on the alternating direction and majorization-minimization (MM) framework is proposed. The numerical results are provided to show the superiority of the proposed algorithm in comparison with a pair of linear frequency modulation (LFM) waveforms with opposite slopes with respect to the anti-ISRJ performance. © 2023 IEEE.

关键词： Iterative methods

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Emotion-Aware Music Driven Movie Montage

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Journal of Computer Science & technology 2023年第3期38卷 540-553页

作者：刘伍琴林敏轩黄海斌马重阳宋玉董未名徐常胜 School of Artificial Intelligence University of Chinese Academy of SciencesBeijing 101408China The State Key Laboratory of Multimodal Artificial Intelligence System(MAIS) Institute of AutomationChinese Academy of SciencesBeijing 100190China Kuaishou Technology Beijing 100085China School of Mechanical Engineering University of Science and Technology BeijingBeijing 100083China

In this paper, we present Emotion-Aware Music Driven Movie Montage, a novel paradigm for the challenging task of generating movie montages. Specifically, given a movie and a piece of music as the guidance, our method aims to generate a montage out of the movie that is emotionally consistent with the music. Unlike previous work such as video summarization, this task requires not only video content understanding, but also emotion analysis of both the input movie and music. To this end, we propose a two-stage framework, including a learning-based module for the prediction of emotion similarity and an optimization-based module for the selection and composition of candidate movie shots. The core of our method is to align and estimate emotional similarity between music clips and movie shots in a multi-modal latent space via contrastive learning. Subsequently, the montage generation is modeled as a joint optimization of emotion similarity and additional constraints such as scene-level story completeness and shot-level rhythm synchronization. We conduct both qualitative and quantitative evaluations to demonstrate that our method can generate emotionally consistent montages and outperforms alternative baselines.

关键词： movie montage emotion analysis audio-visual modality contrastive learning

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The Prosthetic Hand Can Grasp Occluded Objects with the Help of 3rd-Eye Based on Artificial Vision and AR technology 1

The Prosthetic Hand Can Grasp Occluded Objects with the Help...

引用

1st International Conference on Artificial intelligence and Human-Computer Interaction, ArtInHCI 2023

作者： Shi, Chunyuan Zhao, Jingdong State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin150081 China Artificial Intelligence Laboratory Harbin Institute of Technology Harbin150081 China

ISBN: (纸本)9781643685083

Grasping occluded objects is a large challenge for hand amputees because of the hand's perception loss. This paper proposed an alternative approach based on artificial vision and augmented reality technology, termed 3rd-Eye, to solve the problem. In detail, a live stream of an RGB camera attached to the prosthetic hand was presented to the user who wore an augmented reality helmet, HoloLens 2. The 3rd-Eye was integrated into a hybrid control prosthetic system (i-MYO proposed in our previous work). It was tested in a special reach-And-grasp experiment where the subject needed to grasp an occluded object in cluttered environments (one to six objects in total) using the prosthetic hand. The new approach has achieved satisfactory results (success rate: 100% in all). © 2024 The Authors.

关键词： Computer vision

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Rethinking Mutual Information for Language Conditioned Skill Discovery on Imitation Learning 34

Rethinking Mutual Information for Language Conditioned Skill...

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34th International Conference on Automated Planning and Scheduling, ICAPS 2024

作者： Ju, Zhaoxun Yang, Chao Sun, Fuchun Wang, Hongbo Qiao, Yu Academy for Engineering and Technology Fudan University China Shanghai Artificial Intelligence Laboratory China State Key Laboratory of Intelligent Technology and System Tsinghua University China

ISBN: (纸本)9781577358893

Language-conditioned robot behavior plays a vital role in executing complex tasks by associating human commands or instructions with perception and actions. The ability to compose long-horizon tasks based on unconstrained language instructions necessitates the acquisition of a diverse set of general-purpose skills. However, acquiring inherent primitive skills in a coupled and long-horizon environment without external rewards or human supervision presents significant challenges. In this paper, we evaluate the relationship between skills and language instructions from a mathematical perspective, employing two forms of mutual information within the framework of language-conditioned policy learning. To maximize the mutual information between language and skills in an unsupervised manner, we propose an end-to-end imitation learning approach known as Language Conditioned Skill Discovery (LCSD). Specifically, we utilize vector quantization to learn discrete latent skills and leverage skill sequences of trajectories to reconstruct high-level semantic instructions. Through extensive experiments on language-conditioned robotic navigation and manipulation tasks, encompassing BabyAI, LORel, and CALVIN, we demonstrate the superiority of our method over prior works. Our approach exhibits enhanced generalization capabilities towards unseen tasks, improved skill interpretability, and notably higher rates of task completion success. Copyright © 2024, Association for the Advancement of Artificial intelligence (***). All rights reserved.

关键词： Semantics

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Vascular Interventional Surgery Path Planning and 3D Visual Navigation

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Journal of Shanghai Jiaotong University (Science) 2025年第3期30卷 469-477页

作者： Fu, Zeyu Fu, Zhuang Guan, Yisheng State Key Lab of Mechanical System and Vibration Shanghai Jiao Tong University Shanghai200240 China School of Mechanical and Electrical Engineering Guangdong University of Technology Guangzhou510006 China

The introduction of path planning and visual navigation in vascular interventional surgery can provide an intuitive reference and guidance for doctors. In this study, based on the preprocessing results of vessel skeleton extraction and stenosis diagnosis in X-ray coronary angiography images, clustering is used to determine the connectivity of the intersection points, and then the improved Dijkstra algorithm is used to automatically plan the surgical path. On this basis, the intermediate point is introduced to piecewise correct the path and improve the accuracy of the system. Finally, the epipolar constrained inverse projection transformation is used to reconstruct the coronary artery 3D model, and the optimal path is marked to achieve a multi-angle 3D visual navigation. Clinical experimental results show that compared with the traditional Dijkstra algorithm, the improved method can reduce the need for intermediate points, which improves computational efficiency, and the average error of manual calibration path is reduced to 4% of that before overall optimization. The results of 3D reconstruction and reprojection further qualitatively and quantitatively verify the effectiveness of the whole scheme. © Shanghai Jiao Tong University 2023.

关键词： Motion planning

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