Browsing by Author "Wang, Xinyu"

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Cold-Start NOx Mitigation by Passive Adsorption Using Pd-Exchanged Zeolites: From Material Design to Mechanism Understanding and System Integration
(2023-03-07) Li, Ying; Chen, Dongdong; Xu, Xin; Wang, Xinyu; Kang, Running; Fu, Mingli; Guo, Yanbing; Chen, Peirong; Li, Yongdan; Ye, Daiqi
A2 Katsausartikkeli tieteellisessä aikakauslehdessä
It remains a major challenge to abate efficiently the harmful nitrogen oxides (NOx) in low-temperature diesel exhausts emitted during the cold-start period of engine operation. Passive NOx adsorbers (PNA), which could temporarily capture NOx at low temperatures (below 200 °C) and release the stored NOx at higher temperatures (normally 250-450 °C) to downstream selective catalytic reduction unit for complete abatement, hold promise to mitigate cold-start NOx emissions. In this review, recent advances in material design, mechanism understanding, and system integration are summarized for PNA based on palladium-exchanged zeolites. First, we discuss the choices of parent zeolite, Pd precursor, and synthetic method for the synthesis of Pd-zeolites with atomic Pd dispersions, and review the effect of hydrothermal aging on the properties and PNA performance of Pd-zeolites. Then, we show how different experimental and theoretical methodologies can be integrated to gain mechanistic insights into the nature of Pd active sites, the NOx storage/release chemistry, as well as the interactions between Pd and typical components/poisons in engine exhausts. This review also gathers several novel designs of PNA integration into modern exhaust after-treatment systems for practical application. At the end, we discuss the major challenges, as well as important implications, for the further development and real application of Pd-zeolite-based PNA in cold-start NOx mitigation.
Distributed finite-time bipartite consensus of multi-agent systems via event-triggered control
(2020) Xu, Peng; Wang, Xinyu; Xie, Guangming; Tao, Jin; Xu, Minyi; Zhou, Quan
A4 Artikkeli konferenssijulkaisussa
This paper investigates a distributed finite-time event-triggered bipartite consensus control for multi-agent systems. Under scenarios of energy limitation, an event-triggered strategy coupled with a nonlinear distributed control protocol is proposed only relying on local information, where the controller only updates at triggered instants. We proved that when the antagonistic network contains a spanning tree, the event-triggered controller can drive all agents to reach consensus value with an identical magnitude but opposite signs. Moreover, both the convergence time depending on the initial state and the positive lower bound of inter-event times are achieved. Simulation results show that the proposed controller has better disturbance rejection properties and can achieve bipartite consensus faster compared to an asymptotic controller. Copyright (C) 2020 The Authors.
Distributed Self-triggered Circular Formation Control for Multi-robot Systems
(2020-07) Xu, Peng; Wang, Xinyu; Tao, Jin; Xie, Guangming; Xu, Minyi; Zhou, Quan
A4 Artikkeli konferenssijulkaisussa
This paper investigates circular formation control problems for multi-robot systems in the plane via a distributed self-triggered strategy. In scenarios of restricted energies, a distributed self-triggered protocol is designed for controlling multiple robots to converge asymptotically to a prescribed circular orbit around a fixed target. In particular, each robot maintains any desired relative angular distances during its rotation around the target. Besides, no collision among robots is taken place, since the spatial order of robots is preserved throughout the evolution. We prove that when the event-triggered condition is enforced during the whole process, the controllers only update with superior performance. Moreover, Zeno behavior can be ruled out. Numerical simulations demonstrate the feasibility and effectiveness of the theoretical results.
Experimental investigation and numerical simulation of transverse heat flux attenuation during fire in utility tunnel
(2023-12) Pan, Rongliang; Hostikka, Simo; Zhu, Guoqing; Wang, Xinyu; Liu, Xin; Wang, Wei; Lan, Meng
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
To analyze transverse fire protection, the distribution law and evolution mechanism of transverse heat transfer during fire in utility tunnels is required urgently. In this study, the experiment and numerical simulation were employed to investigate the evolution of transverse heat transfer under the curved ceiling. After validation, the fire dynamics simulation models with unstructured geometry were established to predict the transverse heat flux. Through the experiment and simulation, the fire source and target location under the curved ceiling were considered, and the prediction models of heat flux provided by the flame body before the impingement point and the heat flux provided by the extension flame body and thermal environment were proposed. Based on the proposed models, the shift relationship (competition mechanism) between the components provided by flame body before the impingement point and the extension flame body (including the thermal environment) under the curved ceiling was illustrated. The transverse heat flux attenuation of each component in different fire scenarios with different fire sources and target point locations was compared to reveal the competition mechanism among the components in the heat flux. This work provides a reference for the transverse fire protection design and risk assessment in utility tunnels.
Investigation of Viscoelastic Properties of Polymer-Modified Asphalt at Low Temperature Based on Gray Relational Analysis
(2023-04) Huang, Zhongcai; Lu, Rong; Fu, Zhiyu; Li, Jingxiao; Li, Pengfei; Wang, Di; Wei, Ben; Zhu, Weining; Wang, Zujian; Wang, Xinyu
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
As the investigation indexes of low-temperature viscoelastic properties of polymer-modified asphalt (PMA) are unclear at present, in this paper, the creep stiffness (S), creep rate (m), low-temperature continuous classification temperature (TC), ΔTC, m/S, relaxation time ((Formula presented.)), and dissipation energy ratio ((Formula presented.)) were taken as a comparison sequence. The maximum flexural tensile strain (εB) of porous asphalt mixture (PAM) in a low-temperature bending test was selected as a reference sequence. Gray relational analysis was used to investigate the PMA’s low-temperature viscoelastic properties based on a bending beam rheometer (BBR). The results show certain contradictions in investigating the low-temperature properties of PMA when only considering the low-temperature deformation capacity or the stress relaxation capacity. The modulus and relaxation capacity should be considered when selecting the investigation indexes of the low-temperature viscoelastic properties of PMA. When rheological method is used to evaluate the low-temperature of polymer modified asphalt, TC and m/S are preferred. When only S or m is contradictory, m should be preferred. ΔTC can determine whether the low-temperature performance of PMA is dominated by S or m. The result can better guide the construction of asphalt pavement in areas with low temperatures. Asphalt can be selected quickly and accurately to avoid the waste of resources.
Quantitative analysis of the impact of COVID-19 on ship visiting behaviors to ports- A framework and a case study
(2022-11-01) Wang, Xinyu; Liu, Zhao; Yan, Ran; Wang, Helong; Zhang, Mingyang
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Corona Virus Disease 2019 (COVID-19) outbreak leads to a significant downturn in the global economy and supply chain. In the maritime sector, trade volume slumped by 3.8% in 2020 compared with 2019. To explore the impacts of COVID-19 on ship visiting behaviors, a framework is proposed to analyze the impact of COVID-19 on port traffic using Automatic Identification System (AIS) data. Firstly, a ship travel behavior-based model is proposed to identify the vessel anchoring and berthing. Then, the diversity in vessel anchoring and berthing time are analyzed, reflecting the impact of COVID-19. The port congestion caused by COVID-19 is quantified by accounting for the number of visiting ships and their residence time. Finally, a case study is carried out on vessels in the Beibu Gulf, China, operating from 2019 to 2020. The results show that the average anchoring time and berthing time increase by 62% and 11% for cargo ships and by 112% and 63% for oil tankers after the outbreak of COVID-19 compared with that before COVID-19. And the density of ships increases in the port area in 2020. Accordingly, the relevant improvements and countermeasures are proposed to reduce the adverse impact of the epidemic on the port navigation system. The paper has the potential to provide a reference for port management and improving port navigation efficiency in the post-pandemic era.
Research on High- and Low-Temperature Rheological Properties of High-Viscosity Modified Asphalt Binder
(2023-04) Huang, Zhongcai; Ling, Xianwu; Wang, Di; Li, Pengfei; Li, Huaquan; Wang, Xinyu; Wang, Zujian; Wei, Rong; Zhu, Weining; Falchetto, Augusto Cannone
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
This study evaluates the critical high- and low-temperature rheological properties of a high-viscosity modified asphalt (HVMA) binder by analyzing one neat and three high-viscosity modified binders (B-type, Y-type, and H-type) using temperature sweep tests and multi-stress creep recovery tests (MSCR) through the dynamic shear rheometer (DSR), and low-temperature creep stiffness properties by the bending beam rheometer (BBR). Technical indexes such as the softening point temperature, dynamic viscosity, rutting factor, unrecoverable creep compliance, and the creep recovery rate are measured and calculated for high-temperature properties, while the m/S value, dissipation energy ratio, relaxation time, elongation, creep stiffness, and creep speed are used as technical indexes for low-temperature properties. The results show that the incorporation of high-viscosity modifiers reduces the unrecoverable creep compliance and increases the creep recovery rate of the asphalt binder. Non-recoverable creep compliance is found to be a reliable indicator for high-temperature performance, while at low temperatures, the relaxation time decreases, the dissipation energy increases, and the stress relaxation ability improves. The dissipation energy ratio and m/S value are suggested to evaluate the low-temperature performance of HVMA binders using the Burgers model based on the BBR bending creep stiffness test. Therefore, this study recommends using the unrecoverable creep compliance via MSCR to evaluate high-temperature properties and dissipation energy ratio and m/S value for low-temperature properties in the evaluation of HVMA binders.
A triboelectric-based artificial whisker for reactive obstacle avoidance and local mapping
(2021-07-10) Xu, Peng; Wang, Xinyu; Wang, Siyuan; Chen, Tianyu; Liu, Jianhua; Zheng, Jiaxi; Li, Wenxiang; Xu, Minyi; Tao, Jin; Xie, Guangming
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Since designing efficient tactile sensors for autonomous robots is still a challenge, this paper proposes a perceptual system based on a bioinspired triboelectric whisker sensor (TWS) that is aimed at reactive obstacle avoidance and local mapping in unknown environments. The proposed TWS is based on a triboelectric nanogenerator (TENG) and mimics the structure of rat whisker follicles. It operates to generate an output voltage via triboelectrification and electrostatic induction between the PTFE pellet and copper films (0.3mm thickness), where a forced whisker shaft displaces a PTFE pellet (10mm diameter). With the help of a biologically inspired structural design, the artificial whisker sensor can sense the contact position and approximate the external stimulation area, particularly in a dark environment. To highlight this sensor's applicability and scalability, we demonstrate different functions, such as controlling LED lights, reactive obstacle avoidance, and local mapping of autonomous surface vehicles. The results show that the proposed TWS can be used as a tactile sensor for reactive obstacle avoidance and local mapping in robotics.