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MicroFallNet: A lightweight model for real-time fall detection on smart wristbands

PERVASIVE AND MOBILE COMPUTING 2025年 109卷

作者： Hu, Jun Cheng, Feiyan Liu, Meng Xu, Xuanle Li, Xiaojing Yunnan Normal Univ Engn Res Ctr Photoelect Detect & Percept Technol Kunming 650500 Yunnan Peoples R China Yunnan Normal Univ Coll Informat Kunming 650500 Yunnan Peoples R China

Falls are a major public health concern for the aging population, leading to significant injuries, loss of independence, and increased healthcare costs. While wearable devices present promising solutions, existing algorithms are often hindered by the limitations of microcontroller units (MCU) in terms of computational power, memory, and energy consumption. To overcome these challenges, we introduce MicroFallNet, a lightweight convolutional neural network designed for accurate and efficient fall detection. MicroFallNet features a novel FireModel architecture, incorporating Squeeze and Expand layers to optimize computational efficiency and enhance feature extraction. The proposed algorithm demonstrates superior performance on the UMAFALL and FallAllD datasets, achieving geometric mean accuracies of 97.91 % and 97.86 %, respectively, significantly surpassing traditional methods. Additionally, MicroFallNet showcases excellent deployment efficiency across various microcontrollers, particularly excelling on the ESP32 smart wristband platform, where it achieves an inference time of just 30.3 milliseconds. This capability makes MicroFallNet ideally suited for real-time fall detection applications, advancing the development of wearable devices for the elderly and contributing substantially to the field of smart health monitoring. Our code will be publicly available at https://***/qwer12330/ MicroFallNet-A-Lightweight-Model-for-Real-Time-Fall-Detection-on-Smart-Wristbands-Using-Sm.

关键词： Edge artificial intelligence Health monitoring Fall detection FireModel ESP32 smart wristband

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ZnO-TiO2 Binary Compound Core-Shell Nanorods for Selective Sensing of Short-Chain Alcohols

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ACS APPLIED NANO MATERIALS 2025年第12期8卷 5941-5950页

作者： Liu, Yingkai Liu, Lei Li, Yujiang Liu, Shaoyu Zhang, Weibin Zhang, Ruifeng Liu, Yao Rong, Qian Zheng, Jie Yunnan Normal Univ Yunnan Key Lab Optoelect Informat Technol Kunming 650500 Peoples R China Yunnan Normal Univ Inst Phys & Elect Informat Kunming 650500 Peoples R China Yunnan Normal Univ Sch Hosp Kunming 650500 Peoples R China

The regularly ordered core-shell nanorods provide an effective transport channel for the adsorption and desorption of the target molecules. However, it remains a great challenge to precisely control the shell thickness of the ordered core-shell nanorods and improve the catalytic activity of their surfaces due to the complexity of the reaction system, especially by enhancing their selectivity to short-chain alcohols. Herein, we propose ZnO/TiO2 core-shell nanorod arrays (NRs) with different shell thicknesses prepared by electron beam evaporation and found that they possess advanced selectivity for short-chain alcohols. The response time of a ZnO/TiO2 core-shell NR with a TiO2 shell of 30 nm to 100 ppm isoamyl alcohol is 17 s. Its response to 100 ppm of isoamyl alcohol is 807, which is approximately 158 times that of the pure ZnO NR. The ZnO/TiO2 NR (30 nm) sensor exhibited excellent selectivity for methanol, ethanol, isopropanol, n-butanol, and isoamyl alcohol. The response to alcohols increased with the increase of the alcohols' chain length. Its sensing mechanism for short-chain alcohols is explained in terms of adsorption energy, acidity, and electronegativity of H in organic groups by density functional theory in detail. Our results open an alternative route for the design of sensitive materials for the selective detection of short-chain alcohols.

关键词： ZnO/TiO2 core-shell nanorod array gas sensor short-chain alcohols selectivity density functional theory

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Robust gradient aware and reliable entropy minimization for stable test-time adaptation in dynamic scenarios

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VISUAL COMPUTER 2025年第1期41卷 315-330页

作者： Xiong, Haoyu Xiang, Yu Yunnan Normal Univ Sch Informat Sci & Technol Kunming Yunnan Peoples R China

Test-time adaptation (TTA) aims to provide neural networks capable of adapting to the target domain distribution using only unlabeled test data. Most existing TTA methods have achieved success under mild conditions, such as independently sampled data from a single or multiple static domains. However, these attempts may fail in dynamic scenarios, where the test data distribution undergoes continuous changes over time. By digging into the failure cases, we find that high-entropy or noisy samples during long-term adaptation may lead to inevitable catastrophic failure. Thus, we propose a Robust Gradient Aware and Reliable entropy minimization approach, called RGAR, to further stabilize TTA from three aspects: (1) Boosting model robustness to distribution shift, we propose a dual-stream perturbation technique that enables two weak-to-strong perturbation views of the student model guided by a common strong view of the mean teacher model;(2) mitigating the impact of high-entropy samples from different scenarios, we present to minimize the reliable samples that take into account both the distribution shift and sample adaptation degree;(3) enabling the model to be insensitive to small perturbations by encouraging model weights to reach flatter minima while focusing on the maximal gradient norm. Extensive experimental results demonstrate the effectiveness of our proposed method, RGAR. We achieve state-of-the-art performance on widely used benchmark datasets, such as CIFAR10C, CIFAR100C, and ImageNet-C. Our source code is available at https://***/r/D152/.

关键词： Image classification Unsupervised domain adaptation Test-time adaptation Distribution shift

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Numerical Analysis of a Second-Order Algorithm for the Time-Dependent Natural Convection Problem

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COMPUTATIONAL METHODS IN APPLIED MATHEMATICS 2025年第2期25卷 415-439页

作者： Chen, Yiru Yang, Yun-Bo Yunnan Normal Univ Dept Math Kunming Peoples R China Yunnan Normal Univ Yunnan Key Lab Modern Analyt Math & Applicat Kunming Peoples R China Yunnan Normal Univ Key Lab Complex Syst Modeling & Applicat Univ Yunn Kunming Peoples R China

In this paper, a second-order algorithm based on the spectral deferred correction method is constructed for the time-dependent natural convection problem, which allows one to automatically increase the accuracy of a first-order backward-Euler time-stepping method through using spectral integration on Gaussian quadrature nodes and constructing the corrections. A complete theoretical analysis is presented to prove that this algorithm is unconditionally stable and possesses second-order accuracy in time. Numerical examples are given to confirm the theoretical analysis and the effectiveness of our algorithm.

关键词： Natural Convection Problem Backward-Euler Spectral Deferred Correction Finite Element Method Error Estimates

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Ultrahigh-performance photodetectors based on low-dimensional Cs2AgBiBr6/CdS heterojunction

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JOURNAL OF COLLOID AND INTERFACE SCIENCE 2025年第Pt A期679卷 316-323页

作者： Liu, Aimin Ding, Jun Tan, Qiuhong Yang, Peizhi Liu, Yingkai Wang, Qianjin Yunnan Normal Univ Coll Phys & Elect Informat Kunming 650500 Yunnan Peoples R China Yunnan Normal Univ Yunnan Prov Key Lab Photoelect Informat Technol Kunming 650500 Yunnan Peoples R China Yunnan Normal Univ Key Lab Adv Tech & Preparat Renewable Energy Mat Minist Educ Kunming 650500 Peoples R China

Lead-free double perovskite Cs2AgBiBr6 has garnered increasing attention in photoelectric applications owing to its good stability and excellent photoelectric properties. However, the poor carrier transport in Cs2AgBiBr6 thin films constraints their further application in photodetection. To overcome this issue, we have developed an innovative low-dimensional Cs2AgBiBr6/CdS heterojunction photodetector with substantially improved performance. The device achieved a high responsivity of 6.66 x 10(3) A/W, an outstanding specific detectivity of 2.10 x 10(14) Jones, and an impressive external quantum efficiency of 1.88 x 10(6) %. Additionally, the on/off current ratio of the heterojunction device reached an impressive 6.18 x 10(7). These key parameters are significantly better than those of most previously reported Cs2AgBiBr6-based photodetectors. Furthermore, scanning photocurrent mapping and band arrangement analysis were performed to elucidate the mechanism of photocurrent generation and transport in the low-dimensional Cs2AgBiBr6/CdS heterojunction photodetectors. This study highlights the outstanding performance of Cs2AgBiBr6/CdS heterojunction and provides a simple and effective strategy for developing high-performance Cs2AgBiBr6-based photodetectors.

关键词： Cs2AgBiBr6 CdS Heterojunction Photodetector

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Application and prospect of vacuum freeze drying technology in environmental field

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REVIEW OF SCIENTIFIC INSTRUMENTS 2025年第2期96卷 023901页

作者： Liao, Qingdan Yu, Dahua Li, Xitong Yunnan Normal Univ Sch Energy & Environm Sci Kunming 650500 Peoples R China Yunnan Normal Univ Yunnan Prov Renewable Energy Engn Key Lab Kunming 650500 Peoples R China Yunnan Normal Univ Yunnan Prov Observat & Res Stn Soil Degradat & Res Kunming 650500 Peoples R China

Vacuum freeze-drying (VFD) technology has gained extensive application across various sectors, particularly in environmental applications, where it is primarily utilized for the fabrication of environmental functional materials and the conservation of environmental organisms. This technology is applicable to soil enhancement, the remediation of aquatic pollutants, energy storage in thermoelectric materials, and the preservation of bacterial cultures. This review synthesizes the most recent advancements in VFD technology within the environmental domain, elaborating on its technical fundamentals, operational procedures, practical applications, and distinctive benefits. Furthermore, the article explores the prospective development trajectory and potential challenges for this technology in the environmental sector, offering scientific guidance for its continued application and insights into its innovative progression.

关键词： Low temperature drying

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Biomass gasification to syngas of phosphogypsum as gasification agent: Thermogravimetric analysis and gasification performance

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FUEL 2025年 385卷

作者： Zhang, Wei Fang, Yingtong Qian, Sheng Chen, Yubao Li, Xingyong Liu, Na Yunnan Normal Univ Sch Energy & Environm Sci Kunming 650500 Yunnan Peoples R China

Biomass utilization in energy production is often regarded as almost carbon neutral, and biomass gasification has significant potential for obtaining products with more value and potential applications for utilizing agricultural and forestry waste. Meanwhile, Phosphogypsum (PG) is a hazardous solid waste generated as a by-product of the wet process of phosphoric acid production, resulting in significant environmental issues. Based on the above, this work proposed that solid waste be utilized effectively by producing syngas through biomass gasification using PG as a gasification agent. The thermal characteristics of biomass with PG and the distribution of gaseous products were discussed, and the effects of the ratio of PG to biomass (O/B values) and temperature were investigated. The mechanism function and activation energy (Ea) were determined by the model-free (Kissinger-Akahira-Sunose method), model-fitting (Coats and Redfern method), and Malek methods. The results indicate that the solid-phase product of the process is calcium sulfide. The experiment obtained the highest peak mass loss R p2 and comprehensive devolatilization parameter D when the O/B value of 0.5, leading to better devolatilization behavior during the devolatilization stage. The kinetics observed during the devolatilization stage show a decreased activation energy as the reaction progresses. Conversely, it gradually increases during the biochar gasification stage. The primary gaseous product emissions exhibited observable peaks in the devolatilization and biochar gasification stages. A significant amount of methane is released during the biochar gasification phase. Alkali metals and their oxides in PG are believed to serve as catalysts or facilitate the process of tar cracking during gasification.

关键词： Biomass gasification Phosphogypsum Thermochemical conversion Product distribution Kinetic analysis

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An efficient two-grid algorithm based on Newton iteration for the stationary inductionless magnetohydrodynamic system

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APPLIED NUMERICAL MATHEMATICS 2025年 212卷 312-332页

作者： Xia, Yande Yang, Yun-Bo Yunnan Normal Univ Dept Math Kunming 650500 Peoples R China Yunnan Normal Univ Yunnan Key Lab Model Analyt Math & Applicat Kunming 650500 Peoples R China Yunnan Normal Univ Key Lab Complex Syst Modeling & Applicat Univ Yunn Kunming 650500 Peoples R China

In this paper, we propose and analyze a two-grid algorithm based on Newton iteration for solving the stationary inductionless magnetohydrodynamic system. The method involves first solving a small nonlinear system on a coarse grid with grid size H, followed by solving two linear problems on a fine grid with grid size h. These linear problems share the same stiffness matrix but differ only in their right-hand sides. The scaling between the coarse and fine grids is improved by our new method, while the approximate solution retains the same order of convergence as that observed in conventional methods. Furthermore, H0(div,Q) x L20(Q)-conforming finite element pairs are utilized to discretize the current density and electric potential, ensuring that the discrete current density is exactly divergence-free. Stability and convergence analyses are rigorously derived, and L2-error estimates for the velocity are provided. Numerical experiments are presented to verify the theoretical predictions and demonstrate the efficiency of the proposed method.

关键词： Inductionless MHD equations Two-grid method Mixed finite element method Newton iteration

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Restoration of secondary forest in the Greater Mekong Subregion struggles to offset primary forest carbon losses

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GLOBAL AND PLANETARY CHANGE 2025年 249卷

作者： Peng, Zongqi Zhu, Yanhui Yang, Kun Luo, Yi Lu, Xixi Wang, Jiasheng Zhang, Yang Su, Danni Sun, Run Zhang, Mingfeng Ma, Jingcong Liu, Yang Sun, Mengzhu Yunnan Normal Univ Fac Geog Kunming Yunnan Peoples R China Yunnan Normal Univ GIS Technol Resarch Ctr Resource & Environm Wester Minist Educ Kunming Yunnan Peoples R China Natl Univ Singapore Singapore Singapore

The Greater Mekong Subregion (GMS) is experiencing significant changes in forest area, prompting an urgent investigation into whether the alterations in carbon stock from forest loss and restoration can meet the region's need for increased carbon sequestration. Therefore, utilizing remote sensing data such as Landsat and machine learning methods, we established distribution maps of primary and secondary forests and forest carbon density maps for the GMS from 2000 to 2020. By analyzing the gradient effect of forest carbon density across four altitude zones, we investigated the altitude asymmetry of the compensatory effect of secondary forests in the GMS, and predicted the carbon potential of the regional forests. The results indicate that, influenced by human activities, forests in the GMS have transitioned from the loss of primary forests in the 2000s to the recovery of secondary forests in the 2010s. While the rates of area change for loss (-2.22 x 105 ha yr- 1) and recovery (1.97 x 105 ha yr- 1) were similar, an altitude asymmetry caused a regional forest carbon imbalance. The low and mid- altitude regions, with higher carbon density and significant forest loss, can only compensate for 31.50 % of the carbon loss in low-altitude (122.28 TgC) and 47.57 % in mid-altitude (76.25 TgC) through secondary forest recovery. In contrast, the high-altitude region, with lower carbon loss (12.93 TgC) and larger recovery area, results in a forest net carbon sink of 10.66 TgC. Over the next decade, if primary forest loss continues at the current pace, existing secondary forest growth will absorb only 50.41 % of carbon emissions. Therefore, collaboration among GMS countries is essential to protect primary forests and promote secondary forest planting in low to mid-altitude areas for sustainable regional forest carbon development.

关键词： Greater Mekong Subregion Forest carbon storage Carbon balance Human activities

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Optimization of time modulated array antennas based on improved gray wolf optimizer

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AIP ADVANCES 2025年第2期15卷

作者： Zhu, Tianning Liu, Yan Li, Jianhui Zhao, Wanru Yunnan Normal Univ Sch Phys & Elect Informat Kunming Yunnan Province Peoples R China

With the widespread application of intelligent optimization algorithms in engineering and scientific fields, the need for their improvement and optimization is increasingly evident. This paper proposes an Improved Gray Wolf Optimization (IGWO) algorithm based on the Gray Wolf Optimization (GWO) method, aiming to enhance global search capability and convergence speed. The proposed IGWO algorithm integrates goodset initialization and the golden sine strategy to enhance global search efficiency and improve local search accuracy. The algorithm is specifically applied to the temporal modulation optimization of antenna arrays, where the switching durations of array elements are modulated to optimize the synthesis of the radiation pattern. The core goal of temporal modulation is to adjust the switching times of individual elements to alter the array's radiation pattern, achieving effects such as sidelobe suppression, main beam optimization, and reduction of harmonic distortion. Experimental validation using four benchmark functions demonstrates that the IGWO algorithm significantly outperforms traditional algorithms, including the seagull optimization algorithm, hunger games search optimization algorithm, seahorse optimizer, and GWO algorithm, across all test cases. In addition, IGWO is applied to optimize three time-modulation models, particularly those that optimize both connection durations and inter-element spacing simultaneously. Despite higher second harmonic distortion than the differential evolution with wavelet mutation algorithm in some cases, IGWO consistently excels in minimizing fundamental sidelobes, first harmonics, and second harmonics. Experimental results validate the algorithm's fast convergence and high optimization accuracy in optimizing the radiation pattern of antenna arrays, showcasing its effectiveness and practicality in addressing electromagnetic problems. (c) 2025 Author(s). All article content, except where otherwise noted, is licensed under a

关键词： Harmonic distortion

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