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Biometric System for Measuring Gait and Fall Characteristics Captured on Video

JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME 2014年第7期136卷 071005-071005页

作者： Firmani, Flavio Robinovitch, Stephen N. Park, Edward J. Univ Victoria Dept Mech Engn Victoria BC V8W 3P6 Canada Simon Fraser Univ Dept Biomed Physiol & Kinesiol Burnaby BC V5A 1S6 Canada Simon Fraser Univ Sch Mechatron Syst Engn Surrey BC V3T 0A3 Canada

This paper presents a methodology that quantifies gait and fall characteristics from video of real-life fall events. The method consists in selecting on-screen the points on the ground where the feet are in contact with the ground. The essence of the method lies in establishing a transformation from the video frames to the "real world." In projected images, geometric properties such as lengths, angles, and parallelism are not preserved;thus, concepts of projective geometry are applied, namely homography. Because the ground is an invariant plane, using this plane for homography results in a constant transformation. The homographic transformation relies on the accuracy in the selection of on-screen points. An optimization algorithm that minimizes the errors caused by inaccurate on-screen point selection improves the results of the homographic transformation. Experimental trials are conducted at three walking velocities (slow, preferred, and fast) using two video cameras and a GAITRite walkway system. Spatial parameters of two independent video analyses are compared with the GAITRite system, yielding a limit of agreement of step length from -2.12 cm to 2.03 cm. Temporal parameters are less confident due to the existence of dropped frames in the video footage. This method is then used to analyze two real fall events as demonstrative cases. First, the gait characteristics are analyzed before imbalance, and subsequently, the characteristics of stepping are analyzed during the fall. In particular, we propose the stepping/impact angle as the metric that quantifies how much stepping affected the direction of the fall.

关键词： Calibration Errors Gait analysis Geometry Biometry Video cameras optimization algorithms Door frames

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Optimal Path Planning With Minimum Inspection Teams and Balanced Working Hours For Power Line Inspection

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FRONTIERS IN PHYSICS 2022年 10卷

作者： Hu, Zhao-Long Deng, Yuan-Zhang Peng, Hao Han, Jian-Min Zhu, Xiang-Bin Zhao, Dan-Dan Wang, Hui Zhang, Jun Zhejiang Normal Univ Coll Math & Comp Sci Jinhua Peoples R China

Power line inspection plays a significant role in the normal operation of power systems. Although there is much research on power line inspection, the question of how to balance the working hours of each worker and minimize the total working hours, which is related to social fairness and maximization of social benefits, is still challenging. Experience-based assignment methods tend to lead to extremely uneven working hours among the working/inspection teams. Therefore, it is of great significance to establish a theoretical framework that minimizes the number of working teams and the total working hours as well as balances the working hours of inspection teams. Based on two real power lines in Jinhua city, we first provide the theoretical range of the minimum number of inspection teams and also present a fast method to obtain the optimal solution. Second, we propose a transfer-swap algorithm to balance working hours. Combined with an intelligent optimization algorithm, we put forward a theoretical framework to balance the working hours and minimize the total working hours. The results based on the two real power lines verify the effectiveness of the proposed framework. Compared with the algorithm without swap, the total working hours obtained by the transfer-swap algorithm are shorter. In addition, there is an interesting finding: for our transfer-swap algorithm, the trivial greedy algorithm has almost the same optimization results as the simulated annealing algorithm, but the greedy algorithm has an extremely short running time.

关键词： path planning optimization algorithms complex networks balancing working hours power line inspection

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An indirect measurement of rock tensile strength through optimized relevance vector regression models, a case study

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ENVIRONMENTAL EARTH SCIENCES 2021年第22期80卷 748-748页

作者： Fattahi, Hadi Hasanipanah, Mahdi Arak Univ Technol Fac Earth Sci Engn Arak Iran Univ Kashan Dept Min Engn Kashan Iran Duy Tan Univ Inst Res & Dev Da Nang 550000 Vietnam

To design the structure of foundations and tunnels, one of the most important parameters to be well considered is the rock tensile strength (TS). Direct methods of TS measurement, i.e., laboratory experiments, are both costly and time-consuming. Therefore, to measure the rock TS, this paper proposes two novel hybrid optimization models, i.e. relevance vector regression (RVR) optimized by the harmony search (HS) and cuckoo search (CS) algorithms. A database including 76 datasets was constructed through collecting the rock samples from a tunnel site and exposing them to different tests (Brazilian tensile strength, BTS, as output) in laboratory. The proposed models performances were assessed through some statistical metrics, e.g., determination coefficient. The results demonstrated the successful application of RVR-HS and RVR-CS models in predicting BTS. However, the performance of RVR-HS was better than RVR-CS. As a conclusion, the HS algorithm played a great role in optimizing the proposed RVR model.

关键词： Rock tensile strength Brazilian tensile strength Relevance vector regression optimization algorithms

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Accurate prediction of electric vehicles mileage for proactive battery management in varied conditions using multi-criteria approach

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COMPUTERS & ELECTRICAL ENGINEERING 2024年第PartA期119卷

作者： V. Jog, Vivek Simu, Shreyas Don Bosco Coll Engn Comp Engn Dept Margao 403602 Goa India Don Bosco Coll Engn Elect & Comp Engn Dept Margao 403602 Goa India

This research addresses several critical challenges in managing battery aging within Electric Vehicles (EVs). Key challenges include minimizing capacity degradation while maximizing vehicle performance and accurately predicting State of Charge (SoC) under diverse operational conditions. Additionally, integrating factors such as vehicle and battery age, driving cycles, environmental conditions, and regional climate variations posed significant hurdles in achieving comprehensive battery management. To tackle these challenges, the research presents a novel framework integrating an advanced Multihead cross attention-based optimizer with a bidirectional long short-term memory network, further enhanced by the coati optimization algorithm. This innovative approach aims to improve prediction accuracy for critical battery performance metrics, such as SoC and battery lifetime. Implemented and rigorously evaluated using Python, the framework demonstrates a substantial 20% increase in battery performance through detailed SoC and temperature analysis, coupled with an impressive 40% enhancement in battery lifetime. These results highlight the ability to overcome previous challenges and provide robust solutions for effective battery management in real-world EV applications.

关键词： Battery decaying monitoring Electric vehicles Lithium-ion batteries State of charge Machine learning optimization algorithms

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Load frequency control in smart grids: A review of recent developments

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RENEWABLE & SUSTAINABLE ENERGY REVIEWS 2024年第PartA期189卷

作者： Wadi, Mohammed Shobole, Abdulfetah Elmasry, Wisam Kucuk, Ismail Istanbul Sabahattin Zaim Univ Elect Engn Dept Halkalı Cad 281 Halkali Kucukcekmece TR-34303 Istanbul Turkiye Istanbul Kultur Univ Comp Engn Dept Atakoy Yerleskesi E5 Karayolu Uzeri Bakirkoy TR-34158 Istanbul Turkiye

This study provides a comprehensive and fresh review of load frequency control (LFC) in multi-area interconnected power systems (MAIPSs). The central tasks of LFC are to keep frequency variations as minimum as possible to achieve an acceptable level of stability. This research provides a complete view, from early classical control to recent technologies and modern techniques considering strategies, robust, optimal, self -tuning, and adaptive controllers for LFC in MAIPSs. Fuzzy control and earlier and recent optimization algorithms also are analyzed. The linearity, nonlinearity, and uncertainty of LFC models are also investigated. This review emphasizes recent technological advances and novel control strategies. LFC is also considered with the integration of wind, photovoltaic, electric vehicles, and storage devices. Besides, the utilization of machine learning and reinforcement techniques is examined. Further, LFC in smart grids and modern complex power systems concerning limited communication bandwidth, communication failure, and cyber-attacks are also investigated. This review provides an in-depth and detailed diagnosis of the challenges associated with LFC in modern and complex power systems. This work may be valuable for studies and practitioners interested in LFC. It, in detail, investigates future efforts and directions to enhance LFC performance, stability, and reliability in the face of increasing complexity and uncertainty.

关键词： Multi-area interconnected power system (MAIPS) Load frequency control (LFC) optimization algorithms Renewable energy Artificial intelligence (AI) Smart grids Electric vehicles (EVs) Communications failures Cyber attacks

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Design of multilayer sound-absorbing composites with excellent sound absorption properties at medium and low frequency via constructing variable section cavities

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COMPOSITE STRUCTURES 2021年 266卷 113798-113798页

作者： Wang, Xiting Ma, Lifeng Wang, Yansong Guo, Hui Shanghai Univ Engn Sci Sch Mech & Automot Engn Shanghai 201620 Peoples R China

In this work, multilayer composites composed of ethylene-propylene-diene monomer (EPDM) foams and EPDM perforated plates were proposed to improve sound absorption properties at medium and low frequency. Models of composites with variable section cavities were designed and explored the influence of structural parameters on sound absorption coefficient. Numeral calculations results showed that the sound absorption curves of multilayer composites usually have two peaks in 300 -1300 Hz. Compared with the other, the composite composed of one perforated board with variable section cavities and two foams (VFF) shows best sound absorption capacities in low frequency. Two optimization algorithms: artificial fish swarm algorithm (AFSA) and improved particle swarm optimization (I-PSO) were presented to optimize structural parameters of VFF. It is found that the optimization results of I-PSO are better that of AFSA for improving the absorption properties at low medium and frequency. This work provide a simple method and a new idea to improve sound absorption properties of multilayer composites.

关键词： Multilayer composites Sound absorption Medium and low frequency optimization algorithms

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Post-earthquake recover strategy for substations based on seismic resilience evaluation

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ENGINEERING STRUCTURES 2023年第1期279卷

作者： Liu, Xiao Xie, Qiang Liang, Huangbin Zhang, Xiuli Tongji Univ Coll Civil Engn Shanghai 200092 Peoples R China South China Agr Univ Coll Water Conservancy & Civil Engn Guangzhou 510640 Peoples R China

Electrical substations need a sufficient amount of time to repair damaged equipment and restore power after an earthquake. Yet, the devastation and danger inherent in an earthquake requires fastest return to power possible;thus, finding better methods to improve the efficiency of post-earthquake emergency recover is an urgent issue. This paper presents a rapid seismic resilience assessment framework which combines a network model and functional time-varying feature. The authors developed a dual-dimensional functional network model of a typical 220 kV substation built with an emphasis on its connectivity capabilities and the power transmission capacity of its equipment. The model's rapid function status was evaluated based on its network dependence on Bayesian network nodes. The authors' post-earthquake iterative analysis focuses on resource constraint and power user importance. This article shows how the authors obtained the stepped functional time-varying function as a basis for quantification in the post-earthquake recovery process and provides a seismic resilience analysis of the electrical substation. The multi-objective heuristic optimization algorithm was developed to determine an optimal post-earthquake multi-level repair strategy for substation post-earthquake recovery and to determine substation's seismic resilience levels.

关键词： Substation system Functional state model Seismic resilience Rapid assessment method optimization algorithms Recover strategies

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Mitigating local minima in extracting optimal parameters for photovoltaic models: An optimizer leveraging multiple initial populations (OLMIP)

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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 2024年 92卷 367-391页

作者： Choulli, Imade Elyaqouti, Mustapha Arjdal, El Hanafi Saadaoui, Driss Ben Hmamou, Dris Lidaighbi, Souad Elhammoudy, Abdelfattah Abazine, Ismail Ydir, Brahim Ibn Zohr Univ Fac Sci Agadir Lab Mat Signals Syst & Phys Modeling BP 8106 Agadir 80000 Morocco

The accurate identification of parameters in photovoltaic models is of paramount importance to accurately predict the electrical behavior of photovoltaic systems and improve their performance. Nowadays, this task poses a multimodal optimization problem, aiming to find the best combination of parameters that fit the model to real data. This article presents a proposal for an Optimizer Leveraging Multiple Initial Populations (OLMIP) that aims to achieve optimal solutions while effectively avoiding undesirable local optima. By utilizing a separate evolution strategy involving four distinct initial populations, followed by the construction of an elite population, the algorithm can explore multiple regions of the search space and escape local minima. Experiments were conducted with four models: the single diode, double diode, triple diode from RTC France cell, and Photowatt-PWP201 module. The mean squared errors obtained are 9.860219E-04, 9.824849E-04, 9.824849E-04, and 2.425075 E-03, respectively. These results indicate that the algorithm achieves superior or comparable accuracy to that of six competitors. Furthermore, the statistical analysis of the results, including the Wilcoxon and Friedman tests, confirms the robustness and effectiveness of the approach used for parameter estimation in photovoltaic systems. These findings open up new prospects for the improvement and optimization of photovoltaic systems.

关键词： Photovoltaic models Parameter extraction optimization algorithms Local minima Multimodal problems

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AdaDerivative optimizer: Adapting step-sizes by the derivative term in past gradient information

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ENGINEERING APPLICATIONS OF ARTIFICIAL INTELLIGENCE 2023年第1期119卷

作者： Zou, Weidong Xia, Yuanqing Cao, Weipeng Beijing Inst Technol Sch Automation Beijing 100081 Peoples R China Guangdong Lab Artificial Intelligence & Digital Ec Shenzhen 518107 Peoples R China

AdaBelief fully utilizes "belief'' to iteratively update the parameters of deep neural networks. However, the reliability of the "belief'' is determined by the gradient's prediction accuracy, and the key to this prediction accuracy is the selection of the smoothing parameter beta(1). AdaBelief also suffers from the overshoot problem, which occurs when the value of parameters exceeds the value of the target and cannot be changed along the gradient direction. In this paper, we propose AdaDerivative to eliminate the overshoot problem of AdaBelief. The key to AdaDerivative is that the "belief'' of AdaBelief is replaced by the derivative term's exponential moving average (EMA), which can be constructed as (1 -beta(2)) Sigma(i)(i =1) beta(t-t)(2) (g(t) - g(t-1))(2) based on the past and current gradients. We validate the performance of AdaDerivative on a variety of tasks, including image classification, language modeling, node classification, image generation, and object detection tasks. Extensive experimental results demonstrate that AdaDerivative can achieve state-of-the-art performance.

关键词： Deep neural networks optimization algorithms Adam Stochastic gradient descent

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A fast key parameter extraction algorithm for long fiber distributed sensing based on Brillouin scattering

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REVIEW OF SCIENTIFIC INSTRUMENTS 2019年第6期90卷 066101-066101页

作者： Zhao, L. J. Xu, Z. N. Li, Y. Q. Chen, Y. H. Qin, H. North China Elect Power Univ Sch Elect & Elect Engn Baoding 071003 Peoples R China North China Elect Power Univ Sci & Technol Coll Baoding 071003 Peoples R China Guangxi Power Grid Corp Grid Planning & Res Ctr Nanning 530000 Peoples R China

A fast key parameter extraction algorithm is proposed to improve the real-time performance of temperature and strain measurements when performing Brillouin scattering-based fiber-distributed sensing. The algorithm uses a new initial value method that takes the extracted key parameters of the current point in the fiber as the initial guesses for the next point. Based on the old and new initial value method, the existing objective method, optimization algorithm, and convergence criterion, the key parameter extraction algorithms developed are implemented in Matlab using the typical Lorentzian, Gaussian, and pseudo-Voigt profiles. These algorithms are used to extract the parameters over a large range of measured Brillouin spectra for the entire fiber with different averaging times. The results reveal that apart from the case when the frequency sweep spans is less than the linewidth and the pseudo-Voigt profile is used (in this case, the mean computation time of the proposed algorithm is 1.1% larger than that of the referenced algorithm), the proposed algorithm not only ensures high accuracy in extracting the key parameters, but also improves the arithmetic efficiency by 16.3%-49.1%.

关键词： Fiber optical scattering Optical fibers Fiber optic devices optimization algorithms Strain measurement Brillouin spectroscopy

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