FedFN: Feature Normalization for Alleviating Data Heterogeneity Problem in Federated Learning

Federated Learning (FL) is a collaborative method for training models while preserving data privacy in decentralized settings. However, FL encounters challenges related to data heterogeneity, which can result in performance degradation. In our study, we observe that as data heterogeneity increases, feature representation in the FedAVG model deteriorates more significantly compared to classifier weight. Additionally, we observe that as data heterogeneity increases, the gap between higher feature norms for observed classes, obtained from local models, and feature norms of unobserved classes widens, in contrast to the behavior of classifier weight norms. This widening gap extends to encompass the feature norm disparities between local and the global models. To address these issues, we introduce Federated Averaging with Feature Normalization Update (FedFN), a straightforward learning method. We demonstrate the superior performance of FedFN through extensive experiments, even when applied to pretrained ResNet18. Subsequently, we confirm the applicability of FedFN to foundation models.Comment: NeurIPS Workshop: "Federated Learning in the Age of Foundation Models" 202

Model-Free Reconstruction of Capacity Degradation Trajectory of Lithium-Ion Batteries Using Early Cycle Data

Early degradation prediction of lithium-ion batteries is crucial for ensuring safety and preventing unexpected failure in manufacturing and diagnostic processes. Long-term capacity trajectory predictions can fail due to cumulative errors and noise. To address this issue, this study proposes a data-centric method that uses early single-cycle data to predict the capacity degradation trajectory of lithium-ion cells. The method involves predicting a few knots at specific retention levels using a deep learning-based model and interpolating them to reconstruct the trajectory. Two approaches are used to identify the retention levels of two to four knots: uniformly dividing the retention up to the end of life and finding optimal locations using Bayesian optimization. The proposed model is validated with experimental data from 169 cells using five-fold cross-validation. The results show that mean absolute percentage errors in trajectory prediction are less than 1.60% for all cases of knots. By predicting only the cycle numbers of at least two knots based on early single-cycle charge and discharge data, the model can directly estimate the overall capacity degradation trajectory. Further experiments suggest using three-cycle input data to achieve robust and efficient predictions, even in the presence of noise. The method is then applied to predict various shapes of capacity degradation patterns using additional experimental data from 82 cells. The study demonstrates that collecting only the cycle information of a few knots during model training and a few early cycle data points for predictions is sufficient for predicting capacity degradation. This can help establish appropriate warranties or replacement cycles in battery manufacturing and diagnosis processes

Experience of Subjective Symptoms in Euthymic Patients with Bipolar Disorder

Bipolar patients often experience subjective symptoms even if they do not have active psychotic symptoms in their euthymic state. Most studies about subjective symptoms are conducted in schizophrenia, and there are few studies involving bipolar patients. We examined the nature of the subjective symptoms of bipolar patients in their euthymic state, and we also compared it to that of schizophrenia and normal control. Thirty bipolar patients, 25 patients with schizophrenia, and 21 normal control subjects were included. Subjective symptoms were assessed using the Korean version of the Frankfurter Beschwerde Fragebogen (K-FBF) and the Symptom Check List 90-R (SCL90-R). Euthymic state was confirmed by assessing objective psychopathology with the Positive and Negative Syndrome scale of Schizophrenia (PANSS), the Young Mania Rating Scale (YMRS), and the Montgomery Asberg Depression Rating Scale (MADRS). K-FBF score was significantly higher in bipolar patients than in normal controls, but similar to that in schizophrenia patients (F=5.86, p=0.004, R2=2033.6). In contrast, SCL90-R scores did not differ significantly among the three groups. Euthymic bipolar patients experience subjective symptoms that are more confined to cognitive domain. This finding supports the hypothesis that subtle cognitive impairments persists in euthymic bipolar patients

MULTILAYER ELECTROLYTE CELL, SECONDARY BATTERY COMPRISING MULTILAYER ELECTROLYTE CELL AND MANUFACTURING METHOD THEREFOR

The present invention relates to a multilayer electrolyte cell, a secondary battery including the multilayer electrolyte cell, and a manufacturing method thereof, and more particularly, to a multilayer electrolyte cell, in which electrolytes are configured in multiple layers by stacking polymer coating layers containing ceramic solid electrolytes and liquid electrolytes including an ionic liquid in a porous structure base, a secondary battery including the multilayer electrolyte cell, and a manufacturing method thereof

Atomic layer deposition of tungsten and tungsten-based compounds using WCl5 and various reactants selected by density functional theory

Atomic layer deposition (ALD) of metals and metal nitrides consist a major portion of the advanced thin film deposition technology owing to their wide applications in the field of the semiconductor industry. In this regard, the ALD of tungsten (W) is one of the vital processes which is mostly studied using WF6 precursor. However, the presence of corrosive fluorine in WF6 restricts its applications due to severe disadvantages like F-contamination and etching of the deposited films and/or the underlying substrate. Therefore, developing F-free W (FFW) precursor to deposit W (and other W-based compounds like WNx) is of significant importance. The current article investigates several possible routes that can give rise to the successful growth of ALD-W or W-based thin films using WCl5 as an FFW precursor. Density functional theory (DFT) simulation was carried out to check the feasibility of the reactions between a reactant and tungsten chloride as well as to predict the composition of the deposited film. The exothermic reactions for ALD of W metal were realized with H, diethylamine borane (DEAB), and dimethylamine borane (DMAB), whereas it was endothermic for H2, triethylaluminum (TEA), trimethylaluminum (TMA), tert-butyl hydrazine (TBH), and NH3. The detailed reaction mechanisms for predicting the growth of tungsten or tungsten compounds were simulated and are helpful to explain the growth of WNxCy by TBH and WCx by TEA. On the other hand, the experimental findings also confirm the W film deposition with H2 plasma and DEAB, between 200 and 300 degrees C. However, the best quality as-grown W-films (polycrystalline with a resistivity of -395 mu S2-cm) were obtained only with H2 plasma as a reactant, which shows the largest negative reaction energy (Delta E) in DFT calculation. Further, the Cl content of much below 1 atomic% in the as-grown films deposited with H2 plasma was evident. Additionally, the experimental findings also confirmed the deposition of crystalline-W2N when NH3 was used as a reactant

Density functional theory study on the reducing agents for atomic layer deposition of tungsten using tungsten chloride precursor

We studied co-reactants for tungsten chloride precursors by density functional theory calculation to find the proper reducing agent. Tungsten chlorides, WCl6 and WCl5, are gaining attention for the fluorine-free atomic layer deposition (ALD) of tungsten. We created a W4Cl12 cluster by optimizing the number of tungsten and chlorine atoms in the chlorine-passivated tungsten cluster. We predicted the growth of tungsten carbide by the reaction of trimethylaluminum with the cluster, confirming that the cluster can mimic the chlorine-passivated tungsten surface. Then we simulated the reaction between the W4Cl12 cluster and four co-reactants. Possible reaction pathways between the cluster and the co-reactants were simulated to compare the reaction energies and activation energies. All co-reactants of the present work, atomic hydrogen, H-2, SiH4, and B2H6, would act as reducing agents with the reaction energies of -2.07 eV, -0.01 eV, -0.28 eV, and -0.45 eV, respectively. The reducing power was in the order of atomic hydrogen, B2H6, SiH4, and H-2 with activation energies of +0.04 eV, +0.18 eV, +1.18 eV, and +2.32 eV, respectively. B2H6 is the most promising gas-phase candidate due to its low activation energy for reduction and high activation energy for boron incorporation

Optimized End Functionality of Silane-Terminated Liquid Butadiene Rubber for Silica-Filled Rubber Compounds

As the world is shifting from internal combustion engine vehicles to electric vehicles in response to environmental pollution, the tire industry has been conducting research on tire performance to meet the requirements of electric vehicles. In this experiment, functionalized liquid butadiene rubber (F-LqBR) with triethoxysilyl groups at both ends was introduced into a silica-filled rubber compound as a substitute for treated distillate aromatic extract (TDAE) oil, and comparative evaluation was conducted according to the number of triethoxysilyl groups. The results showed that F-LqBRs improved silica dispersion in the rubber matrix through the formation of chemical bonds between silanol groups and the base rubber, and reduced rolling resistance by limiting chain end mobility and improving filler–rubber interaction. However, when the number of triethoxysilyl groups in F-LqBR was increased from two to four, self-condensation increased, the reactivity of the silanol groups decreased, and the improvement of properties was reduced. As a result, the optimized end functionality of triethoxysilyl groups for F-LqBR in silica-filled rubber compound was two. The 2-Azo-LqBR with the optimized functionality showed an improvement of 10% in rolling resistance, 16% in snow traction, and 17% in abrasion resistance when 10 phr of TDAE oil was substituted