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129 results on '"Liu, Li-Yang"'

15. Mechanically recyclable melt-spun fibers from lignin esters and iron oxide nanoparticles: towards circular lignin materials.

Author

Thalakkale Veettil, Unnimaya, Moreno, Adrian, Huertas-Alonso, Alberto J., Morsali, Mohammad, Pylypchuk, Ievgen V., Liu, Li-Yang, and Sipponen, Mika H.

Subjects
IRON oxide nanoparticles, LIGNINS, MICROFIBERS, MELT spinning, HYBRID materials, FIBERS, BLENDED yarn
Abstract

The inferior thermoplastic properties have limited production of melt-spun fibers from lignin. Here we report on the controlled esterification of softwood kraft lignin (SKL) to enable scalable, solvent-free melt spinning of microfibers using a cotton candy machine. We found that it is crucial to control the esterification process as melt-spun fibers could be produced from lignin oleate and lignin stearate precursors with degrees of esterification (DE) ranging from 20–50%, but not outside this range. To fabricate a functional hybrid material, we incorporated magnetite nanoparticles (MNPs) into the lignin oleate fibers by melt blending and subsequent melt spinning. Thermogravimetric analysis and X-ray diffraction studies revealed that increasing the weight fraction of MNPs led to improved thermal stability of the fibers. Finally, we demonstrated adsorption of organic dyes, magnetic recovery, and recycling via melt spinning of the regular and magnetic fibers with 95% and 83% retention of the respective adsorption capacities over three adsorption cycles. The mechanical recyclability of the microfibers represents a new paradigm in lignin-based circular materials. [ABSTRACT FROM AUTHOR]

Published
2023
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26. Towards Observable Urban Visual SLAM

Author

Liu, Li Yang

Subjects
ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION
Abstract

University of Technology Sydney. Faculty of Engineering and Information Technology. Visual Simultaneous Localisation and Mapping (V-SLAM) is the subject of robot state and environment map estimation by drawing inference on camera captured data. It has been a major branch of research and popular in application owing to the rich information and low cost in vision measurement acquisition. However, for applications in urban environments, where the camera-mounted vehicle moves along a straight line direction towards the road scene, a large number of features suffer difficulty in depth estimation due to their small parallax angles, as a result the classical V-SLAM algorithm encounters instability and the system state is often unobservable. This thesis addresses the issue of Urban SLAM observability associated with monocular cameras. It proposes a novel Bundle Adjustment (BA) formulation that addresses the problem from a fundamental approach – by parameterising map points in an on-manifold ray parallax form the SLAM formulation has a stable configuration that guarantees local state observability despite of presence of low parallax features. V-SLAM is known to be highly non-convex from its projective image formation principle. Slight off-optimal initial values easily lead to sub-optimal final state estimates. In Urban SLAM this is further exacerbated by collinear camera motion that causes ambiguity in initial state estimation. A robust initialisation method is proposed in this thesis to provide unique near-optimal initial estimates effectively addressing collinearity issues. For practical use of our algorithm, we demonstrate how the urban scene friendly V-SLAM algorithms are integrated into a real-time Visual Inertial Navigation system (VINS). A series of quantitative analyses are performed on a few benchmark datasets, demonstrating effectiveness of our algorithm in urban environments.

Published
2020

45. Direct Production of Levulinic Acid in One Pot from Hemp Hurd by Dilute Acid in Ionic Liquids

Author

Tulaphol, Sarttrawut, Hossain, Md. Anwar, Rahaman, Mohammad Shahinur, Liu, Li-Yang, Phung, Thanh Khoa, Renneckar, Scott, Grisdanurak, Nurak, and Sathitsuksanoh, Noppadon

Abstract

Levulinic acid, a versatile platform chemical from renewable lignocellulose, can be used for the production of fuels, solvents, and pharmaceuticals. The complex chemical bonds of lignocellulose necessitate reaction conditions at high acid loading, low lignocellulose loading, and high temperature and/or pressure. These harsh reaction conditions degrade the intermediates (5-hydroxymethylfurfural (HMF) and glucose), resulting in a low yield of levulinic acid. Here, we show that combined lignocellulose dissolution in ionic liquids (1-ethyl-3-methylimidazolium chloride) and acid hydrolysis by HCl enables the conversion of hemp hurds to a high yield of levulinic acid (59%) in one pot under a mild reaction condition (120 °C and atmospheric pressure) without additional acid catalysts. The presence of HCl (Brønsted acid) catalyzed cellulose hydrolysis, glucose dehydration, and HMF rehydration in ionic liquid. The addition of Lewis acid catalysts (CrCl3, AlCl3, ZrCl4, and SnCl4) was not necessary. Compared with conventional processes for levulinic acid production, our approach has additional key advantages such as high solid loading (17.5 wt %) and no need to separate intermediate products (glucose and HMF). Furthermore, the incorporation of a lignocellulose dissolution step in ionic liquids makes this one-pot strategy customizable for different types of lignocellulose.

Published
2020
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