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Experimental Study of the Wake of Multi-Rotor Turbine

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SSRN 2022年

作者： Xiong, Xue-Lu Laima, Shujin Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters Ministry of Industry and Information Technology Harbin Institute of Technology Harbin150090 China Key Lab of Structures Dynamic Behavior and Control Ministry of Education Harbin Institute of Technology Harbin150090 China

This paper describes a comparative experimental study of the wake of a multi-rotor turbine and a single-rotor turbine. The wake merge process in the multi-rotor wake is analyzed from various perspectives. A jet-like gap flow region and a momentum redistribution region are found in the region before and after the full merge of the individual rotor wakes, respectively. Compared to the single-rotor wake, the fully merged multi-rotor wake is found to have a slower recovery rate and a lower turbulent kinetic energy. Furthermore, two sources are found for the peak frequency in the multi-rotor wake which results in different peak frequencies at different locations. One of the two sources is the rotor wake meandering with the meandering frequency maintain the same throughout the wake, and another one corresponds to the dynamic of the shear layer in the gap region with its peak frequency decrease in the streamwise direction. The yawed multi-rotor wake is found to be similar to the non-yawed case except for the wake deflection of the yawed case. And the deflection is more pronounced in the yawed multi-rotor wake than in the yawed single-rotor wake which indicates a higher yaw efficiency for the multi-rotor turbine. © 2022, The Authors. All rights reserved.

关键词： Wakes

Enhancing Ultrasonic Flaw Detection by a Nonconvex Sparse Regularization Approach

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SSRN 2023年

作者： Wu, Biao Zhou, Wensong College of Civil Engineering Nanjing Tech University Nanjing211816 China Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education School of Civil Engineering Harbin Institute of Technology Harbin150090 China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters the Ministry of Industry and Information Technology Harbin Institute of Technology Harbin150090 China

Ultrasonic testing has been an important tool for the detection of hidden defects in materials yet its effectiveness is usually compromised by the noise originated from both the testing system and the material being evaluated. Motivated by the prior knowledge that only a small number of defects or reflectors exist within the tested material thus the measured signal can be viewed as a linear combination of a few echoes, a novel signal processing method is proposed in this study where a nonconvex sparse regularization method based on lp-norm (0 © 2023, The Authors. All rights reserved.

关键词： Defects

Efficient Two-Stage Strain/Temperature Measurement Method for Botda System Based on Bayesian Uncertainty Quantification

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SSRN 2022年

作者： Meng, Xianghao Zhang, Dongyu Li, Hui Huang, Yong Key Lab of Structures Dynamic Behavior and Control The Ministry of Education School of Civil Engineering Harbin Institute of Technology Harbin China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters The Ministry of Industry and Information Technology Harbin Institute of Technology Harbin China

Brillouin optical time-domain analysis (BOTDA) is an efficient distributed structural strain/temperature measurement technology by identifying the Brillouin frequency (BF) of the fiber. The original BF identification method involves gradually tuning the scanning frequency of the probe laser light, which is time-consuming. To improve the sensing efficiency of BOTDA, a novel two-stage strain/temperature measurement method is proposed based on Bayesian uncertainty quantification. The method uses the information of a small amount of wide range frequency scanning data in the 1st stage to guide a concentrated scanning of the frequency points in the 2nd stage by employing transitional Markov chain Monte Carlo (TMCMC) algorithm. The second-stage scanning strategy based on Bayesian uncertainty quantification ensures the high confidence for BF identification, so that the number of required scanning points can be significantly reduced without sacrificing the measurement accuracy. Finally, the efficacy of the proposed method is verified using numerical and experimental data. © 2022, The Authors. All rights reserved.

关键词： Uncertainty analysis

Water absorptivity and frost resistance performance of self-ignition coal gangue autoclaved aerated concrete

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Journal of Infrastructure Preservation and Resilience 2021年第1期2卷 1-10页

作者： Cong, Xinyu Tan, Yiqiu Lu, Shuang Wang, Zhaojia Huang, Tianyong School of Transportation Science and Engineering Harbin Institute of Technology Huanghe Road 73 Harbin150090 China School of Civil Engineering Harbin Institute of technology Harbin150090 China Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education 9 Harbin Institute of Technology Harbin150090 China State Key Laboratory of Solid Waste Reuse for Building Materials Beijing Building 11 Materials Academy of Science Research Beijing100041 China

Self-ignition coal gangue (SCG) used as one of precursors to fabricate autoclaved aerated concrete (AAC). Aiming at studying water absorptivity and frost resistance performance of SCG-based AAC (SCGAAC), three-period water absorption tests and freeze-thaw tests were carried out and the corresponding results were recorded and analyzed. In order to modify the water absorptivity of SCGAAC, foam stabilizer was applied to adjust pore structure while calcium stearate was expected to change hydrophilic feature of SCG. It was demonstrated that the compressive strength of SCGAAC containing foam stabilizer or calcium stearate declined at different levels. For water absorption, foam stabilizer failed to decrease the water content and even increased water absorption rates. Calcium stearate controlled water absorption rate successfully although the ultimate water content hardly reduced. All of the SCGAAC samples exhibited intact appearance after 50 freeze-thaw cycles and showed excellent frost resistance performance. Three models were proposed to predict water absorptivity and frost resistance performance of SCGAAC and the corresponding prediction results matched test resulted well. © The Author(s) 2021.

关键词： Coal

考虑非线性相关性影响的结构整体可靠度评估——增强型高阶矩方法

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Acta Mechanica Sinica 2023年第4期39卷 3-13页

作者：宋鹏彦王涛吕大刚 College of Civil Engineering and Architecture Hebei UniversityBaoding071002China School of Transportation Science and Engineering Harbin Institute of TechnologyHarbin150040China Chongqing Research Institute of Harbin Institute of Technology Harbin Institute of TechnologyChongqing401151China Key Lab of Structure Dynamic Behavior and Control of China Ministry of Education Harbin Institute of TechnologyHarbin150090China

考虑随机变量间相关性的复杂工程结构整体可靠性分析仍然是一个挑战,特别是对于非线性相关问题.该文考虑到随机变量之间非线性相关的影响,提出了一种用于结构整体可靠性分析的增强型高阶矩方法.该文首先回顾了传统的Nataf变换,进而通过... 详细信息

考虑随机变量间相关性的复杂工程结构整体可靠性分析仍然是一个挑战,特别是对于非线性相关问题.该文考虑到随机变量之间非线性相关的影响,提出了一种用于结构整体可靠性分析的增强型高阶矩方法.该文首先回顾了传统的Nataf变换,进而通过引入Copula理论提出了广义Nataf变换;其次,采用状态变量描述法统一描述整体可靠性问题对应的功能函数,并发展了基于GL_(2)-偏差点集的状态变量高阶矩估计和灵敏度分析方法;再次,通过改进的最大熵法准确估计了结构整体可靠度;最后,通过两个算例验证了所提方法的准确性和有效性以及考虑随机变量间的非线性相关性对结构整体可靠度影响的必要性.算例结果与蒙特卡洛模拟方法比较表明,随机变量间的非线性相关性对结构的整体可靠度有显著影响,所提方法对结构高阶矩估计和全局可靠度分析具有较高的精度和效率.

关键词：最大熵法非线性相关整体可靠性随机变量状态变量可靠度评估蒙特卡洛模拟方法功能函数

Sensitivity Analysis on Effective Parameters for Snow-Melting Performance on Automatically Snow-Melting Fabric Roof And Application on Practical Structure

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SSRN 2022年

作者： Zou, Jialin Sun, Xiaoying Liu, Qing Key Lab of Structures Dynamic Behavior Control of China Ministry of Education Harbin Institute of Technology Harbin150090 China Key lab of Smart Prevention and Mitigation of Civil Engineering Disasters The Ministry of Industry and Information Technology Harbin Institute of Technology Harbin150090 China

In recent decades, numerous membrane structures have been built in the cold region of China. Nevertheless, collapse caused by uneven snow distribution and snow sliding from the edge of roofs occur frequently. This collapse threatens the people’s lives and property. In order to prevent collapse of membrane structure, the automatically snow-melting fabric roof based on electrical-thermal system is presented in this study. Automatically snow-melting fabric roof based on electrical-thermal systems are environmental friendly and clean for eliminating snow that has accumulated on fabric roof. The main task in design the automatically snow-melting fabric roof is determining heating feasibility. A thermal simulation method for the snow melting process is described. This numerical method can predict surface temperature, snow-free area ratio and the coefficient of variation for temperature when climatic condition and heating wire layout parameters are provided. The model is validated experimentally and the influence analysis between the inputs( the heating wire power and spacing, wind velocity, solar radiation, ambient temperature and snow thickness) and the outputs of snow-melting performance are found by thermal simulation. Finally, the three layout scheme of heating wire have been proposed based on snow distribution of four prevailing wind direction and have been applied to ensure that snow-melting fabric roof based on electrical-thermal system studied are feasible to control thickness of snow layers in practical membrane structure. © 2022, The Authors. All rights reserved.

关键词： Snow

Influence of Mix Proportioning Parameters and Curing Regimes on the Properties of Ultra-High Strength Alkali-Activated Concrete

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SSRN 2023年

作者： He, Haiyu Zhang, Rong Song, Yuhuan Zhi, Xudong Fan, Feng Key Lab of Structures Dynamic Behaviour and Control The Ministry of Education Harbin Institute of Technology Harbin150090 China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters The Ministry of Industry and Information Technology Harbin Institute of Technology Harbin150090 China

This study investigates the influence of mix proportioning parameters and curing regimes on the material properties of alkali-activated binder-based ultra-high strength concrete (AAB-UHSC). The effects of five groups of mix proportioning parameters (i.e., fly ash replacement ratio, silica fume replacement ratio, alkali to binder ratio, water glass modulus, and steel fiber content) and three curing regimes(i.e., ambient curing, standard curing, and hybrid curing) on the workability, compressive strength, flexural strength and microstructure development of AAB-UHSC were systematically evaluated. The results indicated that increasing the steel fiber and silica fume dosage negatively affected the flowability of freshly mixed AAB-UHSC. There existed an optimal alkali-to-binder ratio and water glass modulus in terms of flowability, compressive strength, and flexural strength, but the fly ash replacement ratio had a complex effect on the material performance of the AAB-UHSC. The microstructures of the specimens cured in hybrid curing regimes were denser, and fewer cracks were observed, which resulted in higher strength compared to specimens cured under ambient curing and standard curing conditions. The three types of curing regimes adopted barely alter the phases and molecular bonds of hydration products based on the XRD and FTIR results. In addition, the correlations between the compressive strength of the AAB-UHSC obtained under ambient curing conditions, standard curing conditions, and obtained under hybrid curing and standard curing conditions were analyzed, and the fitted results had higher correlation coefficients (R2). © 2023, The Authors. All rights reserved.

关键词： Compressive strength

A Silicon Monoxide Lithium-Ion Battery Anode with Ultrahigh Areal Capacity

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Nano-Micro Letters 2022年第3期14卷 229-243页

作者： Jiang Zhong Tao Wang Lei Wang Lele Peng Shubin Fu Meng Zhang Jinhui Cao Xiang Xu Junfei Liang Huilong Fei Xidong Duan Bingan Lu Yiliu Wang Jian Zhu Xiangfeng Duan State Key Laboratory for Chemo/Biosensing and Chemometrics College of Chemistry and Chemical EngineeringSchool of Physics and ElectronicsHunan Key Laboratory of Two‑Dimensional MaterialsEngineering Research Center of Advanced Catalysis of the Ministry of EducationHunan UniversityChangsha 410082People’s Republic of China International Graduate School at Shenzhen Tsinghua UniversityShenzhen 518057People’s Republic of China Key Laboratory of Structures Dynamic Behavior and Control of the Ministry of Education Key Laboratory of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information TechnologyHarbin Institute of TechnologyHarbin 150090People’s Republic of China School of Energy and Power Engineering North University of ChinaTaiyuan 030051People’s Republic of China Department of Chemistry and Biochemistry University of CaliforniaLos AngelesCA 90095USA

Silicon monoxide(SiO)is an attractive anode material for next-generation lithium-ion batteries for its ultra-high theoretical capacity of 2680 mAh g−*** studies to date have been limited to electrodes with a rela-tively low mass loading(<3.5 mg cm^(−2)),which has seriously restricted the areal capacity and its potential in practical *** areal capacity with such high-capacity materials is critical for capitalizing their potential in practi-cal ***,we report a monolithic three-dimensional(3D)large-sheet holey gra-phene framework/SiO(LHGF/SiO)composite for high-mass-loading *** specifically using large-sheet holey graphene building blocks,we construct LHGF with super-elasticity and exceptional mechanical robustness,which is essential for accommodating the large volume change of SiO and ensuring the structure integrity even at ultrahigh mass ***,the 3D porous graphene network structure in LHGF ensures excellent electron and ion *** systematically tailoring microstructure design,we show the LHGF/SiO anode with a mass loading of 44 mg cm^(−2)delivers a high areal capacity of 35.4 mAh cm^(−2)at a current of 8.8 mA cm^(−2)and retains a capacity of 10.6 mAh cm^(−2)at 17.6 mA cm^(−2),greatly exceeding those of the state-of-the-art commercial or research ***,we show an LHGF/SiO anode with an ultra-high mass loading of 94 mg cm^(−2)delivers an unprecedented areal capacity up to 140.8 mAh cm^(−2).The achievement of such high areal capacities marks a critical step toward realizing the full potential of high-capacity alloy-type electrode materials in practical lithium-ion batteries.

关键词： Silicon monoxide Large-sheet holey graphene Lithium-ion batteries High mass loading Ultra-high areal capacity

A 4D Digital Recovery of the Morphological Evolvement During Pitting Corrosion in Austenitic Grain Structure

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SSRN 2023年

作者： Wang, Mingzhi Yang, Xu Wang, Zhenbo Wang, Wei School of Civil Engineering Harbin Institute of Technology Harbin150090 China Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin150090 China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters The Ministry of Industry and Information Technology Harbin Institute of Technology Harbin150090 China FAW GROUP Changchun130011 China

Pitting corrosion is one fatal phenomenon in metallic material deterioration. A comprehensive understanding of mesoscale corrosion morphology aids the material design for macroscale resilience. This paper presents a confluence between numerical grain structure reconstruction and multiphase corrosion kinetics. A cellular automaton algorithm is proposed to digitally recover the austenite grain structure through nucleation. Image-based input technique is adopted to perform a grain size distribution comparison between digital and practical austenite grain mesostructure. The morphological evolvement during a nanoscale Lattice Boltzmann corrosion is quantitatively characterized by surface area and surface roundness factor. Single pitting results show that the heterogeneous phase distribution contributed up to 7% of the surface roughness of a single pit in the designed environment. The surface roughness development of single pit corrosion is independent of the damage depth under the designed environment. A damage depth threshold exists to trigger the verticle corrosion pit development towards non-spherical morphology. Multiple pitting results show that grain boundary percolation is crucial to maintain mesostructure integrity. This work suggests that manufactured metallic material with high grain boundary resistivity provides a mesoscale skeleton, providing structural resistance in an environment with anti-corrosion requirement. © 2023, The Authors. All rights reserved.

关键词： Surface roughness