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Domain generalization with semi-supervised learning for people-centric activity recognition

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Science China(Information Sciences) 2025年第1期68卷 171-188页

作者： Jing LIU Wei zhu di LI Xing HU Liang SONG Academy for Engineering & Technology Fudan University Shanghai East-bund Research Institute on Networking Systems of ai School of Optoelectronic Information and Computer Engineering University of Shanghai for Science & Technology

People-centric activity recognition is one of the most critical technologies in a wide range of real-world applications,including intelligent transportation systems, healthcare services, and brain-computer interfaces. Large-scale data collection and annotation make the application of machine learning algorithms prohibitively expensive when adapting to new tasks. One way of circumventing this limitation is to train the model in a semi-supervised learning manner that utilizes a percentage of unlabeled data to reduce the labeling burden in prediction tasks. Despite their appeal, these models often assume that labeled and unlabeled data come from similar distributions, which leads to the domain shift problem caused by the presence of distribution gaps. To address these limitations, we propose herein a novel method for people-centric activity recognition,called domain generalization with semi-supervised learning(DGSSL), that effectively enhances the representation learning and domain alignment capabilities of a model. We first design a new autoregressive discriminator for adversarial training between unlabeled and labeled source domains, extracting domain-specific features to reduce the distribution gaps. Second, we introduce two reconstruction tasks to capture the task-specific features to avoid losing information related to representation learning while maintaining task-specific consistency. Finally, benefiting from the collaborative optimization of these two tasks, the model can accurately predict both the domain and category labels of the source domains for the classification task. We conduct extensive experiments on three real-world sensing datasets. The experimental results show that DGSSL surpasses the three state-of-the-art methods with better performance and generalization.

关键词： activity recognition deep learning domain generalization semi-supervised learning adversarial training

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Recent progress on photoactive nonprecious transition-metal complexes

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Science China Chemistry 2025年第1期68卷 46-95页

作者： Zhong-Liang Gong Hong-Jie Zhang Yan Cheng Jianxun Liu Yuhan ai Yaqin Li Zhihui Feng Qiong Zhang Shaolong Gong Yong Chen Chang-Jiang Yao Yuan-Yuan zhu Liang-Jin Xu Yu-Wu Zhong CAS Key Laboratory of Photochemistry Institute of Chemistry Chinese Academy of Sciences State Key Laboratory of Structural Cemistry Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences School of Chemistry and Chemical Engineering Anhui Key Laboratory of Advanced Catalytic Materials and Reaction EngineeringHefei University of Technology State Key Laboratory of Explosion Science and Safety Protection School of Mechatronical Engineering Beijing Institute of Technology College of Chemistry and Molecular Sciences Hubei Key Lab on Organic and Polymeric Optoelectronic Materials Wuhan University School of Chemistry and Chemical Engineering Anhui University Key Laboratory of Photochemical Conversion and Optoelectronic Materials & CAS-HKU Joint Laboratory on New Materials Technical Institute of Physics and Chemistry Chinese Academy of Sciences

Photoactive complexes of nonprecious transition metals, mainly including those in the first-row and partially the second-row of the Periodic table of elements, have received increasing attention in view of their low cost and long-term sustainability. They are recognized as promising alternatives to noble transition metal complex congeners that have been extensively studied in optoelectronic devices, artificial photosynthesis, photocatalysis, biodiagnostics, and therapeutics, etc. This review is devoted to a comprehensive summary on the classical and recent advances on photoactive nonprecious transition metal complexes, including photoactive Zr, V, Cr, Mo, and W complexes, Mn complexes and hybrids, Fe, Co, Ni, and Cu complexes, and Zn and Cd complexes and hybrids. A particular focus is given on the molecular design, modulation of photophysical and photochemical properties, and applications of the representative and lately-developed nonprecious metal complexes. In addition, a perspective on the future development in this field is provided at the end of this review.

关键词： photoactive metal complexes earth-abundant metals nonprecious metal complexes luminescence photochemistry

Valuation and Hedging Strategy of Currency Options under Regime-Switching Jump-diffusion Model

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Acta Mathematicae Applicatae Sinica 2017年第4期33卷 871-892页

作者： Shou-ting CHEN Xun-di diAO ai-lin zhu School of Mathematics and Physical Science Xuzhou Institute of Technology Xuzhou 221008 China Antai College of Economics & Management Shanghai Jiao Tong University Shanghai 200030 China Risk Management Department Bank of Suzhou Suzhou 215100 China

The main purpose of this thesis is in analyzing and empirically simulating risk minimizing European foreign exchange option pricing and hedging strategy when the spot foreign exchange rate is governed by a Markov-modulated jump-diffusion model. The domestic and foreign money market interest rates, the drift and the volatility of the exchange rate dynamics all depend on a continuous-time hidden Markov chain which can be interpreted as the states of a macro-economy. In this paper, we will provide a practical lognormal diffusion dynamic of the spot foreign exchange rate for market practitioners. We employing the minimal martingale measure to demonstrate a system of coupled partial-differential-integral equations satisfied by the currency option price and attain the corresponding hedging schemes and the residual risk. Numerical simulations of the double exponential jump diffusion regime-switching model are used to illustrate the different effects of the various parameters on currency option prices.

关键词： spot foreign exchange rate regime switching jump0diffusion processes minimal martingale mea-sure European currency options pricing and hedging strategy.

Deep Audio-visual Learning:A Survey

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International Journal of Automation and computing 2021年第3期18卷 351-376页

作者： Hao zhu Man-di Luo Rui Wang ai-Hua Zheng Ran He Anhui Provincial Key Laboratory of Multimodal Cognitive Computation School of Computer Science and TechnologyAnhui UniversityHefei 230601China Center for Research on Intelligent Perception and Computing(CRIPAC)and National Laboratory of Pattern Recognition(NLPR) Institute of AutomationChinese Academy of SciencesBeijing 100190China School of Artificial Intelligence University of the Chinese Academy of SciencesBeijing 100049China Center for Excellence in Brain Science and Intelligence Technology Chinese Academy of SciencesShanghai 200031China

Audio-visual learning,aimed at exploiting the relationship between audio and visual modalities,has drawn considerable attention since deep learning started to be used *** tend to leverage these two modalities to improve the performance of previously considered single-modality tasks or address new challenging *** this paper,we provide a comprehensive survey of recent audio-visual learning *** divide the current audio-visual learning tasks into four different subfields:audiovisual separation and localization,audio-visual correspondence learning,audio-visual generation,and audio-visual representation ***-of-the-art methods,as well as the remaining challenges of each subfield,are further ***,we summarize the commonly used datasets and challenges.

关键词： Deep audio-visual learning audio-visual separation and localization correspondence learning generative models representation learning

The qualitative behavior for approximate dirac-harmonic maps into stationary Lorentzian manifolds

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Science China Mathematics 2022年第8期65卷 1679-1706页

作者： Wanjun ai Miaomiao zhu School of Mathematics and Statistics Southwest UniversityChongqing 400715China School of Mathematical Sciences Shanghai Jiao Tong UniversityShanghai 200240China

For a sequence of approximate dirac-harmonic maps from a closed spin Riemann surface into a stationary Lorentzian manifold with uniformly bounded energy,we study the blow-up analysis and show that the Lorentzian energy identity ***,when the targets are static Lorentzian manifolds,we prove the positive energy identity and the no neck property.

关键词： approximate dirac-harmonic maps blow-up analysis no neck Lorentzian manifolds

The distribution and availability of phosphorus fractions in restored cut slopes soil aggregates:a case study of subalpine road,Southwest China

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Frontiers of Environmental Science & Engineering 2023年第4期17卷 27-39页

作者： Mengke zhu Bocong Huang Shenghao ai Zongyang Liu Xiaoyan ai Meihua Sheng Yingwei ai Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education College of Life SciencesState Key Laboratory of Hydraulics and Mountain River EngineeringSichuan UniversityChengdu 610065China Chengdu Institute of Organic Chemistry Chinese Academy of SciencesChengdu 610041China University of Chinese Academy of Sciences Beijing 100049China

The distribution and availability of phosphorus(P)fractions in restored cut slope soil aggregates,along altitude gradients,were *** were collected at 3009,3347,3654 and 3980 m of *** examined soil aggregates total phosphorus(TP),available phosphorus(AP)and phosphorus activation coefficient(PAC),and discovered that there was no significant difference in TP levels between all four altitudes samples(p>0.05).However,there was a significant difference in AP at 3009,3347 and 3980 m of altitude(pdily as soil aggregates sizes increased,as shown:PAC(3654 m)>PAC(3347 m)>PAC(3009 m)>PAC(3980 m).In all particle size soil aggregates,the distribution of the P fractions was as follows:total inorganic phosphorus(TPi)>total organic phosphorus(TPo)>residual phosphorus(R-P),at 3009,3347 and 3654 m,but a different registry was observed at 3980 m of altitude:TPo>TPi>*** correlation and multiple stepwise regression analysis,it was concluded that active NaHCO_(3)-Pi was the main AP *** was also suggested that more attention should be given to the ratio of small particle size aggregates to increase soil AP *** order to improve the activation capacity and supply of soil P,along with promotion of the healthy development of soil ecosystem on slope land,it was suggest that inorganic P fertilizer and P activator could be added to soil at both low(3009 m)and high altitudes(3980 m).

关键词： Altitude gradient Restored cut slopes Soil aggregates Phosphorus fraction Available phosphorus

Integrated HI emission in galaxy groups and clusters

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Research in Astronomy and Astrophysics 2017年第10期17卷 15-26页

作者： Mei ai Ming zhu Jian Fu National Astronomical Observatories Chinese Academy of Sciences Key Laboratory of Radio Astronomy Chinese Academy of Sciences University of Chinese Academy of Sciences Key Laboratory for Research in Galaxies and Cosmology Shanghai Astronomical Observatory Chinese Academy of Sciences

The integrated HI emission from hierarchical structures such as groups and clusters of galax- ies can be detected by FAST at intermediate redshifts. Here we propose to use FAST to study the evolution of the global HI content of clusters and groups over cosmic time by measuring their integrated HI emissions. We use the Virgo Cluster as an example to estimate the detection limit of FAST, and have estimated the integration time to detect a Virgo type cluster at different redshifts （from z = 0.1 to z ---- 1.5）. We have also employed a semi-analytic model （SAM） to simulate the evolution of HI contents in galaxy clusters. Our simulations suggest that the HI mass of a Virgo-like cluster could be 2-3 times higher and the physical size could be more than 50% smaller when redshift increases from z = 0.3 to z = 1. Thus the integration time could be reduced significantly and gas rich clusters at intermediate redshifts can be detected by FAST in less than 2 hours of integration time. For the local Universe, we have also used SAM simulations to create mock catalogs of clusters to predict the outcomes from FAST all sky surveys. Comparing with the optically selected catalogs derived by cross matching the galaxy catalogs from the SDSS survey and the ALFALFA survey, we find that the HI mass distribution of the mock catalog with 20 s of integration time agrees well with that of observations. However, the mock catalog with 120 s of integration time predicts many more groups and clusters that contain a population of low mass HI galaxies not detected by the ALFALFA survey. A future deep HI blind sky survey with FAST would be able to test such prediction and set constraints on the numerical simulation models. The observational strategy and sample selections for future FAST observations of galaxy clusters at high redshifts are also discussed.

关键词： galaxy clusters -- neutral hydrogen (HI) -- galaxy evolution

Robust Estimation for Partial Functional Linear Regression Model Based on Modal Regression

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Journal of Systems Science & Complexity 2020年第2期33卷 527-544页

作者： YU Ping zhu Zhongyi SHI Jianhong ai Xikai School of Mathematics and Computer Science Shanxi Normal UniversityLinfen 041000China Department of Statistics Fudan UniversityShanghai 200433China

This paper presents a robust estimation procedure by using modal regression for the partial functional linear regression,which combines the common linear model with the functional linear regression *** outstanding merit of the new method is that it is robust against outliers or heavy-tail error distributions while performs no worse than the least-square-based estimation method for normal error *** slope function is fitted by *** suitable conditions,the authors obtain the convergence rates and asymptotic normality of the ***,simulation studies and a real data example are conducted to examine the finite sample performance of the proposed *** the simulation results and the real data analysis confirm that the newly proposed method works very well.

关键词： B-spline functional data analysis functional linear model modal regression

A Closed Form Solution to One dimensional Robin Boundary Problems

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Acta Mathematicae Applicatae Sinica 2012年第3期28卷 549-556页

作者： Chang-li YANG ai-lin zhu Physics Department East China Normal University200062ShanghaiChina School of Finance and Statistics East China Normal University200062ShanghaiChina

Many cellular and subcellular biological processes can be described in terms of diffusing and chemically reacting species （e.g. enzymes）. In this paper, we will use reflected and absorbed Brownian motion and stochastic differential equations to construct a closed form solution to one dimensional Robin boundary problems. Meanwhile, we will give a reasonable explanation to the closed form solution from a stochastic point of view. Finally, we will extend the problem to Robin boundary problem with two boundary conditions and give a specific solution by resorting to a stopping time.

关键词： partial differential equations Robin boundary problem diffusion processes Girsanov's formula