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Abstract This article investigates the robustification of the population-informed-personalized Gaussian sum-extended Kalman filter (PI-P-GSEKF) developed in our prior work and its application to continuous venous oxygen saturation (SvO2) estimation. The PI-P-GSEKF was developed to enable state estimation in systems with extremely large variability. It includes a bank of extended Kalman filters (EKFs), whose operating points (i.e., nominal parameter vectors) are selected via generative sampling followed by Markov Chain Monte Carlo (MCMC) sampling with one-time partial state measurement. The state is estimated as the weighted sum of state estimates from all of the EKFs, with the weight for each EKF calculated based on the likelihood of its prediction at every measurement instant. Despite its adequate performance in general, its state estimate can suffer from high-sensitivity operating points whose inaccuracy with respect to the ground truth operating point results in large EKF errors and adversely impacts the PI-P-GSEKF. We explored two ideas to robustify the PI-P-GSEKF against this challenge: (i) penalizing high-sensitivity operating points in MCMC sampling (called robust MCMC sampling) and (ii) calculating the weights for the EKFs based on the likelihood of their predictions in a measurement horizon (called robust Gaussian summing). We examined the efficacy of these ideas in the context of continuous venous oxygen saturation (SvO2) estimation from arterial oxygen saturation measurement, which is important in critical care and cardiopulmonary medicine but is highly invasive and challenging. The results suggested that both ideas could reduce SvO2 estimation error compared with the standard PI-P-GSEKF ((i): 4%; (ii): 13%; (i) + (ii): 16%, on average). However, how to set the length of the sampling interval for weight calculation remains an open challenge. 

Carbon nanotubes (CNTs) are quasi-one dimensional nanostructures that display both high thermal conductivity for potential thermal management applications and intriguing low-dimensional phonon transport phenomena. In comparison to the advances made in the theoretical calculation of the lattice thermal conductivity of CNTs, thermal transport measurements of CNTs have been limited by either the poor temperature sensitivity of Raman thermometry technique or the presence of contact thermal resistance errors in sensitive two-probe resistance thermometry measurements. Here we report advances in a multi-probe measurement of the intrinsic thermal conductivity of individual multi-walled CNT samples that are transferred from the growth substrate onto the measurement device. The sample-thermometer thermal interface resistance is directly measured by this multi-probe method and used to model the temperature distribution along the contacted sample segment. The detailed temperature profile helps to eliminate the contact thermal resistance error in the obtained thermal conductivity of the suspended sample segment. A differential electro-thermal bridge measurement method is established to enhance the signal-to-noise ratio and reduce the measurement uncertainty by over 40%. The obtained thermal resistances of multiple suspended segments of the same MWCNT samples increase nearly linearly with increasing length, revealing diffusive phonon transport as a result of phonon-defect scattering in these MWCNT samples. The measured thermal conductivity increases with temperature and reaches up to 390 ± 20 W m-1 K-1 at room temperature for a 9-walled MWCNT. Theoretical analysis of the measurement results suggests submicron phonon mean free paths due to extrinsic phonon scattering by extended defects such as grain boundaries. The obtained thermal conductivity is decreased by a factor of 3 upon electron beam damage and surface contamination of the CNT sample. 

Mechanical failure and chemical degradation of device heterointerfaces can strongly influence the long-term stability of perovskite solar cells (PSCs) under thermal cycling and damp heat conditions. We report chirality-mediated interfaces based onR-/S-methylbenzyl-ammonium between the perovskite absorber and electron-transport layer to create an elastic yet strong heterointerface with increased mechanical reliability. This interface harnesses enantiomer-controlled entropy to enhance tolerance to thermal cycling–induced fatigue and material degradation, and a heterochiral arrangement of organic cations leads to closer packing of benzene rings, which enhances chemical stability and charge transfer. The encapsulated PSCs showed retentions of 92% of power-conversion efficiency under a thermal cycling test (−40°C to 85°C; 200 cycles over 1200 hours) and 92% under a damp heat test (85% relative humidity; 85°C; 600 hours).