A Method for Detecting the Existence of an Over-Discharged Cell in a Lithium-Ion Battery Pack via Measuring Total Harmonic Distortion

This paper deals with a method to detect the existence of an over-discharged cell in a lithium-ion battery (LIB) pack by measuring the total harmonic distortion (THD) rate in the voltage response. Over-discharge of the LIB cell reduces the available capacity by irreversible chemical reactions, resulting in serious safety risks such as explosions. Even if only one over-discharged cell exists in the battery pack, it accelerates the decomposition of other cells. In general, the measurement of each cell voltage in a battery pack is required to detect one over-discharged cell. This is because if only the voltage of the battery pack is measured, it cannot be distinguished whether the voltage of each cell is uniformly low or one specific weak cell is over-discharged. The proposed method measures the frequency response through the voltage at only two terminals of the battery pack to detect the presence of one over-discharged cell. When the battery cell is discharged beyond a certain level, the system nonlinearity of the battery pack increases, and it can be detected from the increased THD rate of the battery pack. The proposed method is verified by simulation and measurement

A Method for Monitoring State-of-Charge of Lithium-Ion Cells Using Multi-Sine Signal Excitation

In this paper, a method for monitoring SoC of a lithium-ion battery cell through continuous impedance measurement during cell operation is introduced. A multi-sine signal is applied to the cell operating current, and the cell SoH and SoC can be simultaneously monitored via impedance at each frequency. Unlike existing studies in which cell impedance measurement is performed ex situ through EIS equipment, cell state estimation is performed in situ. The measured impedance takes into account cell temperature and cell SoH, enabling accurate SoC estimation. The measurement system configured for the experiment and considerations for the selection of measurement parameters are described, and the accuracy of cell SoC estimation is presented.DFG, 414044773, Open Access Publizieren 2021 - 2022 / Technische Universität Berli

Development of a Matlab/Simulink Model for Monitoring Cell State-of-Health and State-of-Charge via Impedance of Lithium-Ion Battery Cells

Lithium-ion battery cells not only show different behaviors depending on degradation and charging states, but also overcharge and overdischarge of cells shorten battery life and cause safety problems, thus studies aiming to provide an accurate state of a cell are required. Measurements of battery cell impedance are used for cell SoH and SoC estimation techniques, but it generally takes a long time for a cell in each state to be prepared and cell voltage response is measured when charging and discharging under each condition. This study introduces an electrical equivalent circuit model of lithium-ion cells developed in the MATLAB/Simulink environment. Cell SoC, SoH, temperature, and C-rate are considered for more accurate cell impedance prediction, and the simulation results are verified with the measurement results. The developed model is suitable for use in cell SoC and SoH monitoring studies by successfully outputting cell impedance through real-time prediction of cell voltage during discharge

Remote Bio-Sensing: Open Source Benchmark Framework for Fair Evaluation of rPPG

Remote Photoplethysmography (rPPG) is a technology that utilizes the light absorption properties of hemoglobin, captured via camera, to analyze and measure blood volume pulse (BVP). By analyzing the measured BVP, various physiological signals such as heart rate, stress levels, and blood pressure can be derived, enabling applications such as the early prediction of cardiovascular diseases. rPPG is a rapidly evolving field as it allows the measurement of vital signals using camera-equipped devices without the need for additional devices such as blood pressure monitors or pulse oximeters, and without the assistance of medical experts. Despite extensive efforts and advances in this field, serious challenges remain, including issues related to skin color, camera characteristics, ambient lighting, and other sources of noise, which degrade performance accuracy. We argue that fair and evaluable benchmarking is urgently required to overcome these challenges and make any meaningful progress from both academic and commercial perspectives. In most existing work, models are trained, tested, and validated only on limited datasets. Worse still, some studies lack available code or reproducibility, making it difficult to fairly evaluate and compare performance. Therefore, the purpose of this study is to provide a benchmarking framework to evaluate various rPPG techniques across a wide range of datasets for fair evaluation and comparison, including both conventional non-deep neural network (non-DNN) and deep neural network (DNN) methods. GitHub URL: https://github.com/remotebiosensing/rppg.Comment: 19 pages, 10 figure

Rapid suppression of quantum many-body magnetic exciton in doped van der Waals antiferromagnet (Ni,Cd)PS3

The unique discovery of magnetic exciton in van der Waals antiferromagnet NiPS3 arises between two quantum many-body states of a Zhang-Rice singlet excited state and a Zhang-Rice triplet ground state. Simultaneously, the spectral width of photoluminescence originating from this exciton is exceedingly narrow as 0.4 meV. These extraordinary properties, including the extreme coherence of the magnetic exciton in NiPS3, beg many questions. We studied doping effects using Ni1-xCdxPS3 using two experimental techniques and theoretical studies. Our experimental results show that the magnetic exciton is drastically suppressed upon a few % Cd doping. All these happen while the width of the exciton only gradually increases, and the antiferromagnetic ground state is robust. These results highlight the lattice uniformity's hidden importance as a prerequisite for coherent magnetic exciton. Finally, an exciting scenario emerges: the broken charge transfer forbids the otherwise uniform formation of the coherent magnetic exciton in (Ni,Cd)PS3.Comment: 40 pages, 4 main figures, 13 supporting figures, accepted by Nano Letter

Exciton-driven antiferromagnetic metal in a correlated van der Waals insulator

Collective excitations of bound electron-hole pairs -- known as excitons -- are ubiquitous in condensed matter, emerging in systems as diverse as band semiconductors, molecular crystals, and proteins. Recently, their existence in strongly correlated electron materials has attracted increasing interest due to the excitons' unique coupling to spin and orbital degrees of freedom. The non-equilibrium driving of such dressed quasiparticles offers a promising platform for realizing unconventional many-body phenomena and phases beyond thermodynamic equilibrium. Here, we achieve this in the van der Waals correlated insulator NiPS$_3$ by photoexciting its newly discovered spin-orbit-entangled excitons that arise from Zhang-Rice states. By monitoring the time evolution of the terahertz conductivity, we observe the coexistence of itinerant carriers produced by exciton dissociation and the long-wavelength antiferromagnetic magnon that coherently precesses in time. These results demonstrate the emergence of a transient metallic state that preserves long-range antiferromagnetism, a phase that cannot be reached by simply tuning the temperature. More broadly, our findings open an avenue toward the exciton-mediated optical manipulation of magnetism.Comment: 24 pages, 23 figure

Preliminary Assessment of Celecoxib and Microdiode Pulse Laser Treatment of Diabetic Macular Edema

Purpose: Inflammation may play an important role in the pathogenesis of diabetic macular edema, a major cause of vision loss in persons with diabetes. The purpose of this study was to evaluate combined antiinflammatory therapy and laser approaches for treating patients with diabetic macular edema. Methods: In this prospective, factorial, randomized, multicenter trial, we compared cyclo-oxygenase-2 inhibitor (celecoxib) with placebo and diode grid laser with standard Early Treatment Diabetic Retinopathy Study focal laser treatment in 86 participants with diabetic macular edema. The primary outcome is change in visual acuity of ≥15 letters from baseline, and the secondary outcomes include a 50% reduction in the retinal thickening of diabetic macular edema measured by optical coherence tomography and a 50% reduction in leakage severity on fluorescein angiography. Results: Visual acuity and retinal thickening data from >2 years of follow-up did not show evidence of differences between the medical and laser treatments. However, participants assigned to the celecoxib group were more likely to have a reduction in fluorescein leakage when compared with the placebo group (odds ratio = 3.6; P < 0.01). Conclusion: This short-term study did not find large visual function benefits of treatment with celecoxib or diode laser compared with those of standard laser treatment. A suggestive effect of celecoxib in reducing fluorescein leakage was observed

MATLAB/Simulink model for predicting voltage and impedance during discharge of a lithium-ion battery cell

An electrical equivalent circuit model of a lithium-ion cell is developed in MATLAB/Simulink. Overcharging and over-discharging of lithium-ion battery cells can shorten battery life and cause safety issues. Cells also perform differently with aging conditions. The battery cell impedance can be used to estimate the cell State-of-Charge and cell State-of-Health. However, it takes a long time for cells in each state to be prepared and the cell voltage response during charging and discharging under each condition to be measured. Accurate simulation models eliminate not only the purchase cost of experimental devices, but also the time required for cells to be prepared in different states, and significantly reduce the time required for measurement. Cell impedance output from the simulation model takes into account cell SoC, SoH, temperature, and C-rate. The developed model successfully outputs cell impedance through real-time prediction of cell voltage during discharge. This simulation model is suitable for use in cell SoC and cell SoH monitoring studies