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642 results on '"Liu, Yiyun"'

3. Optimizing Personalized Robot Actions with Ranking of Trajectories

Author

Huang, Hao, Liu, Yiyun, Yuan, Shuaihang, Wen, Congcong, Hao, Yu, Fang, Yi, Goos, Gerhard, Series Editor, Hartmanis, Juris, Founding Editor, Bertino, Elisa, Editorial Board Member, Gao, Wen, Editorial Board Member, Steffen, Bernhard, Editorial Board Member, Yung, Moti, Editorial Board Member, Antonacopoulos, Apostolos, editor, Chaudhuri, Subhasis, editor, Chellappa, Rama, editor, Liu, Cheng-Lin, editor, Bhattacharya, Saumik, editor, and Pal, Umapada, editor

Published
2025
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6. Profiling Intact Glycosphingolipids with Automated Structural Annotation and Quantitation from Human Samples with Nanoflow Liquid Chromatography Mass Spectrometry

Author

Schindler, Ryan L, Oloumi, Armin, Tena, Jennyfer, Alvarez, Michael Russelle S, Liu, Yiyun, Grijaldo, Sheryl, Barboza, Mariana, Jin, Lee-Way, Zivkovic, Angela M, and Lebrilla, Carlito B

Subjects
Medical Biochemistry and Metabolomics, Analytical Chemistry, Biomedical and Clinical Sciences, Chemical Sciences, Generic health relevance, Humans, Glycosphingolipids, Liquid Chromatography-Mass Spectrometry, Reproducibility of Results, Chromatography, Liquid, Sphingolipids, Chromatography, High Pressure Liquid, Other Chemical Sciences, Medical biochemistry and metabolomics, Analytical chemistry, Chemical engineering
Abstract

Sphingolipids are an essential subset of bioactive lipids found in most eukaryotic cells that contribute to membrane biophysical properties and are involved in cellular differentiation, recognition, and mediating interactions. The described nanoHPLC-ESI-Q/ToF methodology utilizes known biosynthetic pathways, accurate mass detection, optimized collision-induced disassociation, and a robust nanoflow chromatographic separation for the analysis of intact sphingolipids found in human tissue, cells, and serum. The methodology was developed and validated with an emphasis on addressing the common issues experienced in profiling these amphipathic lipids, which are part of the glycocalyx and lipidome. The high sensitivity obtained using nanorange flow rates with robust chromatographic reproducibility over a wide range of concentrations and injection volumes results in confident identifications for profiling these low-abundant biomolecules.

Published
2024

12. Progressive Knowledge Transfer Based on Human Visual Perception Mechanism for Perceptual Quality Assessment of Point Clouds

Author

Liu, Qi, Liu, Yiyun, Su, Honglei, Yuan, Hui, and Hamzaoui, Raouf

Subjects
Computer Science - Computer Vision and Pattern Recognition, Electrical Engineering and Systems Science - Image and Video Processing
Abstract

With the wide applications of colored point cloud in many fields, point cloud perceptual quality assessment plays a vital role in the visual communication systems owing to the existence of quality degradations introduced in various stages. However, the existing point cloud quality assessments ignore the mechanism of human visual system (HVS) which has an important impact on the accuracy of the perceptual quality assessment. In this paper, a progressive knowledge transfer based on human visual perception mechanism for perceptual quality assessment of point clouds (PKT-PCQA) is proposed. The PKT-PCQA merges local features from neighboring regions and global features extracted from graph spectrum. Taking into account the HVS properties, the spatial and channel attention mechanism is also considered in PKT-PCQA. Besides, inspired by the hierarchical perception system of human brains, PKT-PCQA adopts a progressive knowledge transfer to convert the coarse-grained quality classification knowledge to the fine-grained quality prediction task. Experiments on three large and independent point cloud assessment datasets show that the proposed no reference PKT-PCQA network achieves better of equivalent performance comparing with the state-of-the-art full reference quality assessment methods, outperforming the existed no reference quality assessment network.

Published
2022

17. A Formal Model of Checked C

Author

Li, Liyi, Liu, Yiyun, Postol, Deena L., Lampropoulos, Leonidas, Van Horn, David, and Hicks, Michael

Subjects
Computer Science - Programming Languages, Computer Science - Software Engineering, D.3.1
Abstract

We present a formal model of Checked C, a dialect of C that aims to enforce spatial memory safety. Our model pays particular attention to the semantics of dynamically sized, potentially null-terminated arrays. We formalize this model in Coq, and prove that any spatial memory safety errors can be blamed on portions of the program labeled unchecked; this is a Checked C feature that supports incremental porting and backward compatibility. While our model's operational semantics uses annotated ("fat") pointers to enforce spatial safety, we show that such annotations can be safely erased: Using PLT Redex we formalize an executable version of our model and a compilation procedure from it to an untyped C-like language, and use randomized testing to validate that generated code faithfully simulates the original. Finally, we develop a custom random generator for well-typed and almost-well-typed terms in our Redex model, and use it to search for inconsistencies between our model and the Clang Checked C implementation. We find these steps to be a useful way to co-develop a language (Checked C is still in development) and a core model of it., Comment: This is an extended version of a paper that appears at the 2022 Computer Security Foundations Symposium

Published
2022

31. Study of Cu-exchanged CHA catalysts for the Selective Catalytic Reduction (SCR) reaction

Author

Liu, Yiyun

Abstract

Eliminating the harmful NOx, which is the major pollutant in the exhaust gas of diesel engines, has long been the pursue of scientists. Cu-chabazite (Cu-CHA) zeolites system developed in 2008 is shown to be an efficient and thermal stable catalyst in the deNOx NH3-SCR reaction and has received intense study since then. Aiming to further improve its catalytic activity, a wide range of characterization techniques has been developed and applied to study the well-defined structures and catalysis. Study of SCR reaction over the Cu-CHA catalysts demands the understanding of active Cu sites, for which loading-dependent behaviour is first studied with UV-Vis spectroscopy and ex-situ EPR spectroscopy together with the reaction evaluation. To further investigate different Cu species, the combination of H2-TPR, NH3-TPD and EPR spectroscopy were applied to quantify the Cu speciation in the catalysts, from which the sequential domination of 2AlCu, 1AlCu and CuO species with increasing Cu loadings was observed. Subsequent study of dehydration and hydrothermal aging processes with EPR also reveals the transformation of Cu species from 1AlCu to 2AlCu through the formation of hydrated complexes and the decomposition of CuOx clusters. On the other hand, the interaction between Cu-CHA catalysts and SCR reactants was studied with in situ FTIR and operando NEXAFS, showing the adsorption of NO and NH3 molecules respectively. Aiming to uncover the key species in the SCR reaction and reveal the origin of different reactivity for 1AlCu and 2AlCu sites, the samples with different Cu distribution was studied with operando X-ray spectroscopy under SCR conditions. With the combination of HERFD-XANES, vtc-XES and time-resolved XAS at transient states, key intermediate CuNOx species is observed to be preferentially formed on the 1AlCu sites, while a framework coordinated CuI(NH3)xOfw species is identified to be the real species causing NH3 inhibition effect, hindering the re-oxidation of CuI especially at 2AlCu sites.

Published
2021

42. Reconstruction of a closed-loop ecological cycle system anchored by large-scale load-balancing biogas and its economic viability assessment.

Author

Li, Jianjun, Liu, Yiyun, Zhang, Yuanjie, Zhu, Jing, Wu, Rongqi, and Zhang, Shihua

Abstract

Biogas can be used for complementary load-balancing with renewable intermittent power, thus maintaining overall energy output stability. However, biogas load balancing is typically used in small-scale distributed energy systems, constrained by factors such as technology and land requirements, making it challenging to scale up. Therefore, this study proposes a closed-loop ecological cycle system, where biogas provides load leveling support for large-scale intermittent power sources in desertified regions dominated by animal husbandry. The biogas slurry and residue produced are used for land restoration and subsequent cultivation of high-quality economic crops, with the resulting straw used for the next round of biogas production. This study conducts an economic assessment of the aforementioned system and analyzes a case study of a load-balancing biogas project in Northwest China. Accounting results indicating that the system’s net present value is 0.108 million yuan/m3, internal rate of return is 0.60%, and payback period is 22 years. Additionally, sensitivity backward deduction analysis identified the reasonable value ranges for key system parameters. According to the results, we offer management recommendations to promote the proposed system, supporting innovative biomass energy utilization and enhancing renewable energy stability.Implications: This research introduces a novel closed-loop ecological cycle system that integrates large-scale peak-shaving biogas with renewable energy sources, offering a sustainable solution for enhancing energy stability and environmental sustainability in desertified areas. The study’s economic evaluation reveals the critical role of ecological restoration costs in the overall viability of such systems, indicating the necessity for policy support to make them economically attractive. Our findings suggest that targeted subsidies, based on the quantified ecological benefits, are essential for incentivizing the adoption of this model. By providing specific conditions under which the system is economically feasible, this work informs policymakers on how to design effective incentive structures, thereby promoting the wider application of biogas and contributing to the goals of sustainable development and climate resilience. The research underscores the importance of integrating economic and ecological considerations to achieve long-term sustainability, making it a valuable reference for future energy policies and practices. [ABSTRACT FROM AUTHOR]

Published
2024
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43. Alterations of oral microbiome and metabolic signatures and their interaction in oral lichen planus.

Author

Yan, Li, Xu, Jingyi, Lou, Fangzhi, Dong, Yunmei, Lv, Shiping, Kang, Ning, Luo, Zhuoyan, Liu, Yiyun, Pu, Juncai, Zhong, Xiaogang, Ji, Ping, Xie, Peng, and Jin, Xin

Subjects
ORAL lichen planus, ORAL microbiology, RANK correlation (Statistics), MACHINE learning, MULTIOMICS
Abstract

Background: Oral lichen planus (OLP) is a chronic oral mucosal inflammatory disease with a risk of becoming malignant. Emerging evidence suggests that microbial imbalance plays an important role in the development of OLP. However, the association between the oral microbiota and the metabolic features in OLP is still unclear. Methods: We conducted 16S rRNA sequencing and metabolomics profiling on 95 OLP patients and 105 healthy controls (HC).To study oral microbes and metabolic changes in OLP, we applied differential analysis, Spearman correlation analysis and four machine learning algoeithms Results: The alpha and beta diversity both differed between OLP and HC. After adjustment for gender and age, we found an increase in the relative abundance of Pseudomonas, Aggregatibacter, Campylobacter, and Lautropia in OLP, while 18 genera decreased in OLP. A total of 153 saliva metabolites distinguishing OLP from HC were identified. Notably, correlations were found between Oribacterium, specific lipid and amino acid metabolites, and OLP's clinical phenotype. Additionally, the combination of Pseudomonas, Rhodococcus and (±)10-HDoHE effectively distinguished OLP from HC. Conclusions: Based on multi-omics data, this study provides comprehensive evidence of a novel interplay between oral microbiome and metabolome in OLP pathogenesis using the oral microbiota and metabolites of OLP patients. [ABSTRACT FROM AUTHOR]

Published
2024
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