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Kalman Filtering for Indoor Pose Estimation on Riemannian Manifolds Using IMU and Acoustics
No full textThis paper presents a novel approach that combines inertial navigation systems (INS) with an acoustic Riemannian-based localization system to enhance indoor pose tracking. The proposed method employs an Extended Kalman Filter (EKF) to fuse data from the two systems. The Riemannian-based localization system delivers high-accuracy estimates of the target's pose, which is then used to correct the INS data. A new projection algorithm is introduced to map the EKF output onto the Riemannian manifold, further improving the accuracy of the estimation. Our results show that the proposed method significantly outperforms benchmark algorithms. The effectiveness of the proposed method was evaluated through our in-house experimental setupThis research was supported by KAUST and the Ibn Rushd Postdoctoral Fellowship
ECPv2: Fast, Efficient, and Scalable Global Optimization of Lipschitz Functions
No full textWe propose ECPv2, a scalable and theoretically grounded algorithm for global optimization of Lipschitz-continuous functions with unknown Lipschitz constants. Building on Every Call is Precious (ECP) framework, which ensures that each accepted function evaluation is potentially informative, ECPv2 addresses key limitations of ECP, including high computational cost and overly conservative early behavior. ECPv2 introduces three innovations: (i) an adaptive lower bound to avoid vacuous acceptance regions, (ii) a Worst- memory mechanism that restricts comparisons to a fixed-size subset of past evaluations, and (iii) a fixed random projection to accelerate distance computations in high dimensions. We theoretically show that ECPv2 retains ECP’s no-regret guarantees with optimal finite-time bounds and expands the acceptance region with high probability. We further empirically validate these findings through extensive experiments and ablation studies. Using principled hyperparameter settings, we evaluate ECPv2 across a wide range of high-dimensional, non-convex optimization problems. Across benchmarks, ECPv2 consistently matches or outperforms state-of-the-art optimizers, while significantly reducing wall-clock time
Light extraction improvement via ITO p-electrodes for InGaN red micro-LEDs emitting at 640 nm
No full textWe present light extraction efficiency (LEE) improvement for InGaN red micro-light emitting diodes (micro-LEDs) of various sizes operating at low current densities. We compared the characteristics of micro-LEDs with indium tin oxide (ITO) transparent p-electrodes with conventional opaque metal p-electrodes. 50 µm × 50 µm micro-LEDs with ITO p-electrodes achieved a peak on-wafer external quantum efficiency (EQE) of 2.54% with an emission wavelength of 640 nm at a current density as low as 0.4 A/cm2. This represents a 1.18-fold improvement in peak EQE compared to devices with metal p-electrodes. Light ray tracing simulation confirmed that the ITO p-electrodes exhibit 1.18 times higher light escape than metal-based micro-LEDs, validating the role of enhanced light extraction. These findings provide valuable insights for advancing high-definition display and VR applications.C.A. and K.O. thanks to the KAUST Al-Khawarizmi Ph.D. Scholarship Program. Micro-LEDs reported in this work were fabricated in KAUST Nanofabrication Cleanroom
Impact of Hydroxypropyl Guar Polymer on rheology and filtration properties of water-based drilling fluids
No full textWater-based drilling muds (WBM) are a very crucial component of the oil and gas industry; however, they often face challenges with inadequate rheological performance and excessive fluid loss. This paper introduces Hydroxypropyl Guar Polymer (HPG) and fly ash (FA) as new additives to regulate the rheological properties and filtration loss of WBM. The primary objectives of this study are to reduce filtration loss, enhance rheological characteristics, reduce clay swelling, improve cutting dispersion, and control barite sag. The experimental procedure involves formulating optimized mud samples by incorporating HPG and FA up to 120 °C. The synergistic effect of HPG and FA enhances rheological properties and achieves a 56.52% reduction in filtration loss compared to WBM without additives. Additionally, HPG/FA incorporation resulted in controlling the clay swelling. The swelling dropped from 91.5% to 36.7% compared to the base mud. Shale cuttings recovery in the base fluid was 52.4% after hot rolling at 90 °C, 60 °C, and 40 °C for 16 h and treatment with 0.18% HPG inhibitors improved recovery to 82.1%, 54.1%, and 57.2%, respectively. The sag factor remained controlled compared to the base mud, staying within the acceptable range of 0.503–0.521 at both vertical and 45° inclined angles. The WBM with the addition of HPG and FA is more efficient and has enhanced the well integrity and reduced operational costs in the oil and gas industry.The authors express their gratitude to the Department of Petroleum Engineering at Pandit Deendayal Energy University, Gandhinagar, Gujarat, India, for generously providing the necessary laboratory facilities essential for conducting this research
Cationic Conjugated Polymers with Enhanced Doped-State Planarity for n-Type Organic Thermoelectrics
No full textTo date, extensive efforts have been devoted to designing new conjugated polymers with long alkyl or ethylene glycol sidechains. However, these sidechains are insulators, limiting further performance enhancement in doped conjugated polymers. Moreover, the most widely used chlorinated solvents are toxic, limiting the practical applications of many conjugated polymers. Here, we report a water/ alcohol processable n-type conjugated polymer P(Py2FT), featuring side chain-free cationic backbones. P(Py2FT) exhibits a high n-type electrical conductivity of up to 28.1 S cm−1 and a high thermoelectric power factor of up to 28.7 μW m−1 K−2, comparable to some conventional n-type conjugated polymers reported recently. More importantly, cationic polymers display tight molecular packings and interesting enhanced backbone planarity after n-doping, which, we envision, provides a new research direction to address the sidechain issue in conventional conjugated polymers. Our work demonstrates that sidechain-free cationic polymers have great potential for green-solvent-processed heavily doped organic electronics.This work is supported financially by the National Key R&D Program of China (grant no. 2022YFE0130600), the National Natural Science Foundation of China (grant nos. 22075001 and 92156019), and the King Abdullah University of Science and Technology (KAUST) Competitive Research Grants under award no. ORA-CRG10-2021-4668. X.G. and Y.W. gratefully acknowledge support from the KAUST Office of Sponsored Research under award no. OSA-CRG2021-4668. The computational part of this work is supported by the High-performance Computing Platform of Peking University. We gratefully acknowledge the Molecular Materials and Nanofabrication Laboratory in the College of Chemistry, Electron Microscopy Laboratory, and Materials Processing and Analysis Center of Peking University for the use of their instruments
Organocatalyzed Copolymerization of CO2 with Epoxide Toward Polycarbonate Synthesis
No full textBefore 2016, all research attempts at copolymerizing CO2 with epoxides were exclusively focusing on developing and improving the efficiency of organometallic catalysts. After the first report in 2016 on CO2 /epoxide copolymerization under metal-free conditions, organocatalyzed copolymerization of CO2 with epoxide toward polycarbonate synthesis has emerged as a new and dynamic research topic and great progress has been made over the past eight years. This chapter will first review the copolymerization of CO2 with various epoxides using a bicomponent trialkylborane (TAB)/Lewis’s base system, from the discovery of triethylborane (TEB)-mediated CO2 /epoxides copolymerization, including organo-copolymerizable oxirane monomers, to the design of diverse TAB/Lewis pair systems and a vast array of organocatalyzed polycarbonate-based polymers and block copolymers synthesized. Lastly, more recent works related to bifunctional organoboron catalysts for CO2 /epoxide copolymerization will also be discussed
A formal vinylogous Schmidt reaction: nitrogen insertion of <i>para</i>-quinone methides
No full textCompared with recent nitrogen addition reactions, which mainly focus on the styrene motif, feasible modification of a conjugated C(sp2)–C(sp2) single bond is rare due to its robustness. Herein, we report a facile nitrogen introduction to the conjugated C(sp2)–C(sp2) bond of p-QMs through a vinylogous Schmidt process, using N-OTs carbamate as a bench-stable ambiphilic nitrogen source. Depending on the electron-donating ability of the ortho-substituent on the benzene ring, the reaction underwent the formal vinylogous Schmidt process through an aziridine intermediate or a 1,6-addition/cyclization step delivering benzoxazolidine or dihydroindazole scaffolds, respectively. This study not only expands the application boundary of the Schmidt reaction but also provides a new strategy for nitrogen addition to a C(sp2)–C(sp2) bond.This work was supported by Shandong Provincial Natural Science Foundation (ZR2021QB038, ZR2022QB069), the Natural Science Foundation of China (22101154), Excellent Young Scholars of Shandong Provincial Natural Science Foundation (2022HWYQ-008), Taishan Scholar Youth Program of Shandong Province (tsqnz20230623) and Academic Promotion Program of Shandong First Medical University (2019LJ003). We acknowledge the KAUST Supercomputing Laboratory for providing computational resources from the supercomputer Shaheen II
Error Feedback Approach for Quantization Noise Reduction of Distributed Graph Filters
No full textThis work introduces an error feedback approach for reducing quantization noise of distributed graph filters. It comes from error spectrum shaping techniques from state-space digital filters, and therefore establishes connections between quantized filtering processes over different domains. Quantization noise expression incorporating error feedback for finite impulse response (FIR) and autoregressive moving average (ARMA) graph filters are both derived with regard to time-invariant and time-varying graph topologies. Theoretical analysis is provided, and closed-form error weight coefficients are found. Numerical experiments demonstrate the effectiveness of the proposed method in noise reduction for the graph filters regardless of the deterministic and random graph topologies
Salen-Type Copper(II) Complexes: Synthesis, Characterization, Computational Studies, Molecular Docking, Anticancer Potential, and Pharmacokinetic Prediction
No full textTransition metal complexes are considered a significant treatment for cancer diseases because of their efficacy toward cancer cells. However, most of these compounds have limited potential toward cancer cells due to their organic backbone structure. Here, the synthesis and anticancer screening of three different ligand structures of salen copper(II) complexes are reported: [CuII(salophen)(H2O)2] (1), [CuII(salen)(H2O)2] (2), and [CuII(etho-salen)(H2O)2] (3). Using density functional theory-optimized structures, docking active site interactions are evaluated to predict the activity of salen-type ligands and their copper(II) complexes against cyclin-dependent kinase 5 (Cdk5 ) and aromatase cytochrome (P450) proteins. The molecular docking study reveals that among all studied ligands and complexes, [CuII(salen)(H2O)2] (2) has the best docking score value, S = −8.79 and −7.73, with the lowest root mean square deviation (RMSD = 1.02 and 1.09) against proteins Cdk5 and P450, respectively. Anticancer activity against MCF-7 and HCT-116 cell lines reveals that [CuII(salen)(H2O)2] (2) shows favorable behavior with IC50 values of 212.5 and 98.9 μm, respectively. Its parent ligand 2 shows lower potency, with IC50 values of 404.7 μm in MCF-7 and 305.2 μm in HCT-116. Notably, copper(II) complexes display reduced toxicity rather than cisplatin toward normal HFF-1 fibroblasts, indicating a more favorable therapeutic window.The authors gratefully acknowledge King Abdulaziz University (KAU) and King Abdullah University of Science and Technology (KAUST) for providing the facilities for analysis and measurements
Valorization of Residual Oils for Advanced Carbon Materials
No full textThe utilization of residual petroleum oils as a source of high-value carbon-based materials is an innovative pathway toward sustainable resource valorization. This work begins with a comprehensive analysis of heavy residues, highlighting their valuable composition through gas, liquid, and solid analyses following pyrolysis reactions over a broad temperature range (400-1000°C). The results constitute a valuable dataset essential for modeling heavy residues across different upgrading processes. In addition, this work presents a novel surrogate formulation approach based on high-resolution mass spectrometry. This method facilitates the representation of heavy residues without the burden of data analysis across different analytical techniques. The surrogates generated by this semi-automated method yield single- or multicomponent surrogates that reproduce elemental and functional group moieties while enabling the prediction of physical properties, thereby significantly reducing the analytical burden typically associated with surrogate modeling.
Beyond conventional upgrading techniques, this work also demonstrated the potential of heavy residues as a valuable carbon source. First, the synthesis of graphene quantum dots (GQDs) from all four SARA fractions: saturates, aromatics, resins, and asphaltenes via a mild, H₂O₂-assisted hydrothermal method is presented. Characterization via TEM and photoluminescence spectroscopy revealed that while particle sizes remained consistently below 10 nm, optical behavior was primarily governed by surface chemistry inherited from the parent fractions. This establishes
a new strategy for tailoring GQD properties by selecting fractions at the precursor level. Finally, the potential of residual oils as an alternative precursor for carbon fiber production is presented. We demonstrate for the first time the role of petroleum resins in improving the processability and mechanical performance of asphaltene-based fibers. Blending resins with asphaltenes enhanced spinnability, stabilization behavior, and carbon yield, resulting in fibers with mechanical properties comparable to those of conventional isotropic carbon fibers.
Together, these studies offer a comprehensive approach for the chemical transformation of residual oils into functional and structural carbon materials, highlighting their viability as sustainable precursors for next-generation energy and materials applications