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Top-k contrast order-preserving pattern mining

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arXiv 2023年

作者： Wu, Youxi Meng, Yufei Li, Yan Guo, Lei Zhu, Xingquan Fournier-Viger, Philippe Wu, Xindong School of Artificial Intelligence Hebei University of Technology Tianjin300401 China Shijiazhuang University of Applied Technology Shijiazhuang050081 China School of Economics and Management Hebei University of Technology Tianjin300401 China State Key Laboratory of Reliability and Intelligence of Electrical Equipment Hebei University of Technology Tianjin300401 China Department of Computer & Electrical Engineering and Computer Science Florida Atlantic University FL33431 United States Shenzhen University Shenzhen China Research Center for Knowledge Engineering The Zhejiang Lab Hangzhou311121 China

Recently, order-preserving pattern (OPP) mining, a new sequential pattern mining method, has been proposed to mine frequent relative orders in a time series. Although frequent relative orders can be used as features to classify a time series, the mined patterns do not reflect the differences between two classes of time series well. To effectively discover the differences between time series, this paper addresses the top-k contrast OPP (COPP) mining and proposes a COPP-Miner algorithm to discover the top-k contrast patterns as features for time series classification, avoiding the problem of improper parameter setting. COPP-Miner is composed of three parts: extreme point extraction to reduce the length of the original time series, forward mining, and reverse mining to discover COPPs. Forward mining contains three steps: group pattern fusion strategy to generate candidate patterns, the support rate calculation method to efficiently calculate the support of a pattern, and two pruning strategies to further prune candidate patterns. Reverse mining uses one pruning strategy to prune candidate patterns and consists of applying the same process as forward mining. Experimental results validate the efficiency of the proposed algorithm and show that top-k COPPs can be used as features to obtain a better classification performance. Copyright © 2023, The Authors. All rights reserved.

关键词： Time series

Biopharma innovation trends during COVID-19 and beyond: an evidence from global partnerships and fundraising activities, 2011-2022

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Globalization and Health 2023年第1期19卷 57-57页

作者： Yu, Tzu-Hui Mei, Yung-Yu Tseng, Yufeng Jane Department of Economics National Taiwan University No. 1 Sec. 4 Roosevelt Road Taipei Taiwan Science & Technology Policy Research and Information Center National Applied Research Laboratories No. 106 Heping East Road Taipei Taiwan Department of Computer Science and Information Engineering National Taiwan University No. 1 Sec. 4 Roosevelt Road Taipei Taiwan Graduate Institute of Biomedical Electronics and Bioinformatics National Taiwan University No. 1 Sec. 4 Roosevelt Road Taipei Taiwan

Background: Co-development alliances and capital-raising activities are essential supports for biopharmaceutical innovation. During the initial outbreak of the COVID-19, the level of these business activities has increased greatly. Yet the magnitude, direction, and duration of the trend remain ambiguous. Real-time real-world data are needed to inform strategic redirections and industrial policies. Methods: This observational study aims to characterize trends in global biopharma innovation activities throughout the global pandemic outbreak. Our extensive deal dataset is retrieved from the commercial database GlobalData (12,866 partnership deals and 32,250 fundraising deals announced between 2011 and 2022). We perform Chi-squared tests to examine the changes in qualitative deal attributes during and beyond the outbreak. Our deal-level sample is further aggregated into category-level panel data according to deal characteristics such as therapy area, molecule type, and development phase. We run a series of regressions to examine how the monthly investment amount raised in each category changed with the onset of the pandemic, controlling for the US Federal funds rate. Results: The temporary surge of partnership and capital-raising activities was associated with the increase in infectious disease-related deals. Academic and government institutions played an increased role in supporting COVID-related co-development partnerships in 2020, and biopharma ventures had been securing more investments in the capital market throughout 2020 and 2021. The partnership and investment boom did not last till the later pandemic in 2022. The most significant and enduring trend was the shifting focus toward discovery-phase investments. Our regression model reveals that the discovery-phase fundraising deals did not suffer from a bounce back in the late pandemic, consistent with a persistent focus on early innovation. Conclusions: Despite the reduced level of partnership and fundraising activ

关键词： Biopharmaceutical industry COVID-19 Fundraising Innovation Partnership

Characterization of Magnetic Flux Contents for Flux Transfer Events and its Implications for Flux Rope Formation at the Earth’s Magnetopause

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arXiv 2023年

作者： Wang, Shuo Zou, Ying Hu, Qiang Shi, Xueling Hasegawa, Hiroshi The University of Alabama in Huntsville HuntsvilleAL35805 United States Johns Hopkins University Applied Physics Laboratory LaurelMD United States Department of Space Science The University of Alabama in Huntsville HuntsvilleAL35805 United States Department of Electrical and Computer Engineering Virginia Tech BlacksburgVA United States High Altitude Observatory National Center for Atmospheric Research BoulderCO United States Sagamihara Japan

Flux transfer events (FTEs) are a type of magnetospheric phenomena that exhibit distinctive observational signatures from the in-situ spacecraft measurements across the Earth’s magnetopause. They are generally believed to possess a magnetic field configuration of a magnetic flux rope and formed through magnetic reconnection at the dayside magnetopause, sometimes accompanied with enhanced plasma convection in the ionosphere. We examine two FTE events under the condition of southward interplanetary magnetic field (IMF) with a dawn-dusk component at the magnetopause by applying the Grad-Shafranov (GS) reconstruction method to the in-situ measurements by the Magnetospheric Multiscale (MMS) spacecraft to derive the magnetic flux contents associated with the FTE flux ropes. In particular, given a cylindrical magnetic flux rope configuration derived from the GS reconstruction, the magnetic flux content can be characterized by both the toroidal (axial) and poloidal fluxes. We then estimate the amount of magnetic flux (i.e., the reconnection flux) encompassed by the area "opened" in the ionosphere, based on the ground-based Super Dual Auroral Radar Network (SuperDARN) observations. We find that for event 1, the FTE flux rope is oriented in the approximate dawn-dusk direction, and the amount of its poloidal magnetic flux agrees with the corresponding reconnection flux. For event 2, the agreement among the estimates of the magnetic fluxes is uncertain. We provide a detailed description about our interpretation for the topological features of the FTE flux ropes, based on a formation scenario of sequential magnetic field reconnection between adjacent field lines, consistent with our results. © 2023, CC BY-NC-SA.

关键词： Magnetic flux

Additively Manufactured Flow Manifolds Enable High Performance Direct Cooling for High Density Power Electronics

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SSRN

SSRN 2022年

作者： Lad, Aniket Ajay Tayade, Ashrit Hoque, Muhammad Jahidul Mahmud, Mohammad Hazzaz Diao, Fei Wu, Yuheng Zhao, Yue Balda, Juan Carlos King, William P. Miljkovic, Nenad Department of Mechanical Science and Engineering University of Illinois at Urbana-Champaign UrbanaIL United States Materials Research Laboratory University of Illinois at Urbana-Champaign UrbanaIL United States Materials Science and Engineering University of Illinois at Urbana Champaign UrbanaIL United States Department of Electrical and Computer Engineering University of Illinois at Urbana-Champaign UrbanaIL United States Kyushu University 744 Motooka Nishi-ku Fukuoka819-0395 Japan Department of Electrical Engineering University of Arkansas FayettevilleAR72701 United States

Single phase liquid cooled heat sinks are a preferred for thermal management in many power dense electronics cooling applications. This paper shows how an additively manufactured (AM) polymer manifold coupled with a direct cooling approach can provide high performance cooling for power electronic converters. We experimentally demonstrate a 50% reduction in mass of the power converter subsystem using our polymer cooling manifolds while maintaining comparable junction-to-coolant thermal resistance ( [[EQUATION]] 0.3 K/W) to state-of-the-art (SOA) metal cold plates ( [[EQUATION]] 0.2 K/W). We demonstrate the validity of our approach using experimental performance characterization of channel, zig-zag, and serpentine AM cooling manifolds. Three-dimensional (3D) computational fluid dynamics (CFD) predict thermal-hydraulic performance over a range of operating conditions and the predictions compare well with experimental results. The introduction of channel flow enables lower thermal resistance ( [[EQUATION]] 0.17 K/W) and chip-to-chip temperature variation ( © 2022, The Authors. All rights reserved.

关键词： 3D printers

HySparK: Hybrid Sparse Masking for Large Scale Medical Image Pre-Training

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arXiv 2024年

作者： Tang, Fenghe Xu, Ronghao Yao, Qingsong Fu, Xueming Quan, Quan Zhu, Heqin Liu, Zaiyi Zhou, S. Kevin School of Biomedical Engineering Division of Life Sciences and Medicine University of Science and Technology of China Anhui Hefei230026 China Suzhou Institute for Advanced Research University of Science and Technology of China Jiangsu Suzhou215123 China Institute of Computing Technology CAS Beijing100190 China Department of Radiology Guangdong Provincial People’s Hospital Guangdong Academy of Medical Sciences Guangzhou China Guangdong Provincial Key Laboratory of Artificial Intelligence in Medical Image Analysis and Application Guangdong Provincial People’s Hospital Guangdong Academy of Medical Sciences Guangzhou China

The generative self-supervised learning strategy exhibits remarkable learning representational capabilities. However, there is limited attention to end-to-end pre-training methods based on a hybrid architecture of CNN and Transformer, which can learn strong local and global representations simultaneously. To address this issue, we propose a generative pre-training strategy called Hybrid Sparse masKing (HySparK) based on masked image modeling and apply it to large-scale pre-training on medical images. First, we perform a bottom-up 3D hybrid masking strategy on the encoder to keep consistency masking. Then we utilize sparse convolution for the top CNNs and encode unmasked patches for the bottom vision Transformers. Second, we employ a simple hierarchical decoder with skip-connections to achieve dense multi-scale feature reconstruction. Third, we implement our pre-training method on a collection of multiple large-scale 3D medical imaging datasets. Extensive experiments indicate that our proposed pre-training strategy demonstrates robust transfer-ability in supervised downstream tasks and sheds light on HySparK’s promising prospects. The code is available at https://***/FengheTan9/HySparK. Copyright © 2024, The Authors. All rights reserved.

关键词： Self-supervised learning

Instruction-ViT: Multi-Modal Prompts for Instruction Learning in ViT

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arXiv 2023年

作者： Xiao, Zhenxiang Chen, Yuzhong Zhang, Lu Yao, Junjie Wu, Zihao Yu, Xiaowei Pan, Yi Zhao, Lin Ma, Chong Liu, Xinyu Liu, Wei Li, Xiang Yuan, Yixuan Shen, Dinggang Zhu, Dajiang Liu, Tianming Jiang, Xi School of Life Science and Technology University of Electronic Science and Technology of China Chengdu611731 China Department of Computer Science and Engineering The University of Texas at Arlington Arlington76019 United States School of Computing The University of Georgia Athens30602 United States Glasgow College University of Electronic Science and Technology of China Chengdu611731 China School of Automation Northwestern Polytechnical University Xi’an710072 China Department of Electronic Engineering Chinese University of Hong Kong Hong Kong Department of Radiotion Oncology Mayo Clinic Arizona United States Department of Radiology Massachusetts General Hospital Harvard Medical School Boston02115 United States School of Biomedical Engineering ShanghaiTech University Shanghai201210 China Shanghai United Imaging Intelligence Co. Ltd. Shanghai200230 China Shanghai Clinical Research and Trial Center Shanghai201210 China

Prompts have been proven to play a crucial role in large language models, and in recent years, vision models have also been using prompts to improve scalability for multiple downstream tasks. In this paper, we focus on adapting prompt design based on instruction tuning into a visual transformer model for image classification which we called Instruction-ViT. The key idea is to implement multi-modal prompts (text or image prompt) related to category information to guide the fine-tuning of the model. Based on the experiments of several image captionining tasks, the performance and domain adaptability were improved. Our work provided an innovative strategy to fuse multi-modal prompts with better performance and faster adaptability for visual classification models. Copyright © 2023, The Authors. All rights reserved.

关键词： Image enhancement

Inexact Bregman Proximal Gradient Method and its Inertial Variant with Absolute and Partial Relative Stopping Criteria

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arXiv 2021年

作者： Yang, Lei Toh, Kim-Chuan School of Computer Science and Engineering Guangdong Province Key Laboratory of Computational Science Sun Yat-Sen University China Department of Mathematics Institute of Operations Research and Analytics National University of Singapore Singapore119076 Singapore

The Bregman proximal gradient method (BPGM), which uses the Bregman distance as a proximity measure in the iterative scheme, has recently been re-developed for minimizing convex composite problems without the global Lipschitz gradient continuity assumption. This makes the BPGM appealing for a wide range of applications, and hence it has received growing attention in recent years. However, most existing convergence results are only obtained under the assumption that the involved subproblems are solved exactly, which is unrealistic in many applications and limits the applicability of the BPGM. To make the BPGM implementable and practical, in this paper, we develop inexact versions of the BPGM (denoted by iBPGM) by employing either an absolute-type stopping criterion or a partial relative-type stopping criterion for solving the subproblems. The O(1/k) convergence rate and the convergence of the sequence are also established for our iBPGM under some conditions. Moreover, we develop an inertial variant of our iBPGM (denoted by v-iBPGM) and establish the O(1/kγ) convergence rate, where γ ≥ 1 is a restricted relative smoothness exponent depending on the smooth function in the objective and the kernel function. Specially, when the smooth function in the objective has a Lipschitz continuous gradient and the kernel function is strongly convex, we have γ = 2 and thus the v-iBPGM improves the convergence rate of the iBPGM from O(1/k) to O(1/k2), in accordance with the existing results on the exact accelerated BPGM. Finally, some preliminary numerical experiments for solving the discrete quadratic regularized optimal transport problem are conducted to illustrate the convergence behaviors of our iBPGM and v-iBPGM under different inexactness settings. Copyright © 2021, The Authors. All rights reserved.

关键词：

BOSS: BIDIRECTIONAL ONE-SHOT SYNTHESIS OF ADVERSARIAL EXAMPLES

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arXiv 2021年

作者： Alkhouri, Ismail R. Velasquez, Alvaro Atia, George K. Department of Electrical and Computer Engineering University of Central Florida OrlandoFL United States Information Directorate Air Force Research Laboratory RomeNY United States Department of Computer Science University of Central Florida OrlandoFL United States

The design of additive perturbations to the inputs of classifiers has become a central focus of adversarial machine learning. An alternative approach is to synthesize adversarial examples using structures akin to generative adversarial networks, albeit with the use of large amounts of training data. By contrast, this paper considers the one-shot synthesis of adversarial examples that requires only a single reference datum. In particular, we explore solutions where the generated data must simultaneously satisfy user-defined constraints on its structural similarity to the reference input datum and the output of the classifier of interest it induces. This gives rise to what we call the Bidirectional One-Shot Synthesis (BOSS) problem. We prove that the BOSS problem is NP-complete. The experimental results verify that the targeted and confidence reduction attack methods developed either outperform or on par with state-of-the-art methods. © 2021, CC BY.

关键词： Generative adversarial networks

Facile access to chiral 4-substituted chromanes through Rh-catalyzed asymmetric hydrogenation

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Chinese Chemical Letters 2020年第7期31卷 1859-1862页

作者： Lin Tao Qingyang Zhao Xumu Zhang Xiu-Qin Dong Key Laboratory of Biomedical Polymers Engineering Research Centre of Organosilicon Compounds&MaterialsMinistry of EducationCollege of Chemistry and Molecular SciencesWuhan UniversityWuhan 430072China Department of Chemistry and Shenzhen Grubbs Institute Southern University of Science and TechnologyShenzhen 518055China School of Pharmaceutical Sciences(Shenzhen) Sun Yat-sen UniversityShenzhen 518107China

Rh/ZhaoPhos-catalyzed asymmetric hydroge nation of a series of(E)-2-(chro man-4-ylidene)acetates was successfully developed to prepare various chiral 4-substituted chromanes with high yields and excellent enantioselectivities(up to 99%yield,98%ee).Moreover,the gram-scale hydrogenation could be performed well in the presence of 0.02 mol%catalyst loading(TON=5000),the hydrogenation product was easily converted to access other important compounds,which demonstrated the synthetic utility of this asymmetric catalytic methodology.

关键词： Chiral 4-substituted chromanes Asymmetric hydrogenation Excellent enantioselectivity Gram-scale synthesis Bisphosphine-thiourea ligand