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32 results on '"Xiong, Xiaoxia"'

7. High‐Efficiency Iridium‐Yttrium Alloy Catalyst for Acidic Water Electrolysis.

Author

Xiong, Xiaoxia, Tang, Jialin, Ji, Yuan, Xue, Weiqing, Wang, Haoyuan, Liu, Chunxiao, Zeng, Hongliang, Dai, Yizhou, Peng, Hong‐Jie, Zheng, Tingting, Xia, Chuan, Liu, Xinyan, and Jiang, Qiu

Subjects
*HYDROGEN evolution reactions, *WATER electrolysis, *OXYGEN evolution reactions, *CATALYST structure, *CATALYSTS, *THERMAL shock, *ALLOYS
Abstract

Proton exchange membrane (PEM) water electrolysis holds great promise in revolutionizing clean energy production by enabling the efficient generation of hydrogen. Nevertheless, a formidable challenge persists in the realm of designing electrocatalysts that are both highly active and acid‐resistant during the oxygen evolution reaction (OER), thereby mitigating the substantial kinetic barrier. In this study, the facile synthesis of iridium‐yttrium (IrY) alloy nanocatalysts via a thermal shock method is introduced, which exhibits exceptional activity in the context of acidic water oxidation. Through the strategic incorporation of dispersed Y into the lattice of Ir metal, the IrY catalyst demonstrates a notably low overpotential of 255 mV at a current density of 10 mA cm−2 and showcases remarkable catalytic stability in acidic electrolytes, enduring for over 500 h with a high current density of 100 mA cm−2. Through a comprehensive set of in situ characterizations and analytical methods, the formation of a surface Ir‐based oxide layer, induced by deprotonation and electrochemical oxidation is unveiled, which is notably stabilized by the presence of Y dopants. This stabilization of the active site imparts enhanced resistance to over‐oxidation and dissolution, underpinning the exceptional stability of the catalyst. Theoretical calculations suggest that the incorporation of Y into the catalyst structure has a significant impact on enhancing the reactivity of the oxygen intermediate (O*) at adjacent Ir sites, thus lowering the overpotential and promoting OER activity. The alloying approach presents a straightforward method for achieving atomic‐level modifications in catalyst design and can pave the way for the development of more effective and economically viable OER catalysts and beyond. [ABSTRACT FROM AUTHOR]

Published
2024
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22. A forward collision avoidance algorithm based on driver braking behavior

Author

Xiong, Xiaoxia (author), Wang, M. (author), Cai, Yingfeng (author), Cheng, Long (author), Farah, H. (author), Hagenzieker, M.P. (author), Xiong, Xiaoxia (author), Wang, M. (author), Cai, Yingfeng (author), Cheng, Long (author), Farah, H. (author), and Hagenzieker, M.P. (author)

Abstract

Measuring risk is critical for collision avoidance. The paper aims to develop an online risk level classification algorithm for forward collision avoidance systems. Assuming risk levels are reflected by braking profiles, deceleration curves from critical evasive braking events from the Virginia “100-car” database were first extracted. The curves are then clustered into different risk levels based on spectrum clustering, using curve distance and curve changing rate as dissimilarity metrics among deceleration curves. Fuzzy logic rules of safety indicators at critical braking onset for risk classification were then extracted according to the clustered risk levels. The safety indicators include time to collision, time headway, and final relative distance under emergency braking, which characterizes three kinds of uncertain critical conditions respectively. Finally, the obtained fuzzy risk level classification algorithm was tested and compared with other Automatic Emergency Braking (AEB) algorithms under Euro-NCAP testing scenarios in simulation. Results show the proposed algorithm is promising in balancing the objectives of avoiding collision and reducing interference with driver's normal driving compared with other algorithms., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Transport and Planning

Published
2019
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26. Multi-Level Prediction Framework of Driving Risk Based on the Matter-Element Extension Model

Author

Xiong, Xiaoxia, He, Yu, Cai, Yingfeng, Liu, Qingchao, Wang, Hai, and Chen, Long

Abstract

Surrogate safety measures (SSMs) can be used alone or in combination to assess vehicle conflicts. However, considering the complexity and uncertainty of the traffic environment, the road traffic factors that can be accounted for are still limited by combining two or more SSMs. This study proposes a driving risk prediction framework based on a modified matter-element extension model (MEEM), which integrates a set of carefully selected indicators at the macro-road-section level, the meso-vehicle-group level, and the micro-adjacent-vehicle level, to comprehensively reflect the factors affecting road traffic safety in temporal, spatial, and vehicular dimensions. To validate the proposed framework, lane-changing trajectories from the highD dataset are extracted to obtain the multi-level indicators and clustered risk levels. Different combinations of the multi-level indicators in different proportions are examined. The results show that the multi-level indicator combinations outperform those with micro-level indicators only, and optimal prediction performance is achieved when the ratio of meso- and micro-level indicators approaches 4:6. Furthermore, different time advances of the macro-level indicators are compared and analyzed considering flow propagation effect. It is found that an appropriate setting of the time advance in the calculation of macro-level indicators can help improve the accuracy of risk prediction. Finally, compared with the baseline algorithm random forest, MEEM generally shows better prediction performance at different prediction time, indicating that the multi-level indicators can be more effectively fused to assess risk using the proposed MEEM.

Published
2024
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30. The Cost of Right-of-Way acquisitions for transportation projects : switching models for condemnation versus negotiated settlement

Author

Xiong, Xiaoxia

Subjects
Right of Way acquisition, Cost estimation, Condemnation, Endogenous switching regression
Abstract

The costs of acquiring parcels by condemnation are usually significantly higher than those for property acquired by negotiation, suggesting that Right-of-Way (R/W) acquisition costs may best be described by two different regression equations. This paper develops a switching regression model of acquisition cost to simultaneously predict the probability of whether a parcel will go to condemnation rather than be acquired via negotiation and the corresponding acquisition costs under these two regimes. The error terms of the selection equation and the two cost equations follow a trivariate normal distribution to reflect correlations across unobserved factors (such as a land owner's tenacity or a site's view value). When this model is calibrated using data on properties acquired across the state of Texas for transportation projects between 2008 and 2011, results suggest that R/W appraisers and staff should pay special attention to commercially used parcels in urban areas involving a partial taking with a relatively small remainder. Comparison of cost estimates between the two regimes (condemnation vs. negotiation) suggests that condemned parcels will have, on average, 78% higher acquisition costs across the 1,710 acquired properties and 51% greater price variation. These results suggest that it is much more costly to acquire a property and more difficult to accurately predict its costs if it cannot be acquired via negotiation. The application of model estimates to an example corridor highlights the value of simulation to capture all modeling uncertainties. This two-regime model is further extended to a three-category multinomial endogenous switching, allowing for differential cost estimates across negotiation-deed, administrative settlement, and condemnation contexts. A model of acquisition time -- from the agency's initial-offer date to its final possession date is also developed, to examine the effects of condemnation on acquisition duration. The results suggest that condemnation proceedings add approximately 7 to 8 months, on average, to parcel acquisitions by the Texas Department of Transportation. Taken together, such switching models for condemnation versus negotiated settlement highlight the benefits of avoiding condemnation proceedings in R/W acquisition. Estimation results illuminate the relative importance of various parcel and owner attributes, impacting the nature and cost of acquisition, and enhancing opportunities for R/W staff to identify more contentious properties and establish more reliable budget estimates.

Published
2012

31. Ruthenium Single-Atom Modulated Protonated Iridium Oxide for Acidic Water Oxidation in Proton Exchange Membrane Electrolysers.

Author

Tang J, Liu X, Xiong X, Zeng Q, Ji Y, Liu C, Li J, Zeng H, Dai Y, Zhang X, Li C, Peng H, Jiang Q, Zheng T, Pao CW, and Xia C

Abstract

Proton exchange membrane water electrolysers promise to usher in a new era of clean energy, but they remain a formidable obstacle in designing active and durable electrocatalysts for the acidic oxygen evolution reaction (OER). In this study, a protonated iridium oxide embedded with single-atom dispersed ruthenium atoms (H 3.8 Ir 1- x Ru x O 4 ) that demonstrates exceptional activity and stability in acidic water oxidation is introduced. The single Ru dopants favorably induce localized oxygen vacancies in the Ir─O lattice, synergistically strengthening the adsorption of OOH* intermediates and enhancing the intrinsic OER activity. In addition, the preferential oxidation of Ru and the electronegativity of the oxygen vacancies significantly stabilize the Ir─O active sites, improving the OER stability. Consequently, the H 3.8 Ir 1─ x Ru x O 4 catalyst shows an overpotential of 255 mV at 10 mA cm -2 and displays exceptional catalytic endurance in acidic electrolytes, surpassing 1100 h, representing a remarkable one-order-of-magnitude increase in stability compared to that of pristine H 3.8 IrO 4 . A proton exchange membrane electrolyser utilizing the H 3.8 Ir 1- x Ru x O 4 catalyst as an anode exhibits stable performance for more than 1280 h under a high current density of 2 A cm -2 ., (© 2024 Wiley‐VCH GmbH.)

Published
2024
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