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Non-convex sparse optimization-based impact force identification with limited vibration measurements

《机械工程前沿（英文）》 2023年 第18卷 第3期 doi: 10.1007/s11465-023-0762-2

摘要： Impact force identification is important for structure health monitoring especially in applications involving composite structures. Different from the traditional direct measurement method, the impact force identification technique is more cost effective and feasible because it only requires a few sensors to capture the system response and infer the information about the applied forces. This technique enables the acquisition of impact locations and time histories of forces, aiding in the rapid assessment of potentially damaged areas and the extent of the damage. As a typical inverse problem, impact force reconstruction and localization is a challenging task, which has led to the development of numerous methods aimed at obtaining stable solutions. The classical ℓ2 regularization method often struggles to generate sparse solutions. When solving the under-determined problem, ℓ2 regularization often identifies false forces in non-loaded regions, interfering with the accurate identification of the true impact locations. The popular ℓ1 sparse regularization, while promoting sparsity, underestimates the amplitude of impact forces, resulting in biased estimations. To alleviate such limitations, a novel non-convex sparse regularization method that uses the non-convex ℓ1−2 penalty, which is the difference of the ℓ1 and ℓ2 norms, as a regularizer, is proposed in this paper. The principle of alternating direction method of multipliers (ADMM) is introduced to tackle the non-convex model by facilitating the decomposition of the complex original problem into easily solvable subproblems. The proposed method named ℓ1−2-ADMM is applied to solve the impact force identification problem with unknown force locations, which can realize simultaneous impact localization and time history reconstruction with an under-determined, sparse sensor configuration. Simulations and experiments are performed on a composite plate to verify the identification accuracy and robustness with respect to the noise of the ℓ1−2-ADMM method. Results indicate that compared with other existing regularization methods, the ℓ1−2-ADMM method can simultaneously reconstruct and localize impact forces more accurately, facilitating sparser solutions, and yielding more accurate results.

关键词： impact force identification     inverse problem     sparse regularization     under-determined condition     alternating direction method of multipliers    

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A dynamic stiffness-based framework for harmonic input estimation and response reconstruction considering damage

Yixian LI; Limin SUN; Wang ZHU; Wei ZHANG

《结构与土木工程前沿（英文）》 2022年 第16卷 第4期   页码 448-460 doi: 10.1007/s11709-022-0805-5

摘要： In structural health monitoring (SHM), the measurement is point-wise but structures are continuous. Thus, input estimation has become a hot research subject with which the full-field structural response can be calculated with a finite element model (FEM). This paper proposes a framework based on the dynamic stiffness theory, to estimate harmonic input, reconstruct responses, and to localize damages from seriously deficient measurements. To begin, Fourier transform converts the dynamic equilibrium equation to an equivalent static one in the frequency domain, which is under-determined since the dimension of measurement vector is far less than the FEM-node number. The principal component analysis has been adopted to “compress” the under-determined equation, and formed an over-determined equation to estimate the unknown input. Then, inverse Fourier transform converts the estimated input in the frequency domain to the time domain. Applying this to the FEM can reconstruct the target responses. If a structure is damaged, the estimated nodal force can localize the damage. To improve the damage-detection accuracy, a multi-measurement-based indicator has been proposed. Numerical simulations have validated that the proposed framework can capably estimate input and reconstruct multi-types of full-field responses, and the damage indicator can localize minor damages even with the existence of noise.

关键词： dynamic stiffness     principal component analysis     response reconstruction     damage localization     under-determined equation    

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亚奈奎斯特采样的数据恢复：性能极限与恢复算法

罗茜倩,张朝阳

《信息与电子工程前沿（英文）》 2021年 第22卷 第2期   页码 141-286 doi: 10.1631/FITEE.1900320

摘要： 奈奎斯特频率是一般带限信号进行无损采样的采样率下界，然而在某些情景中，亚奈奎斯特频率也足以进行无损采样和信号恢复。以往对亚奈奎斯特采样的研究主要集中在利用信号变换来降低信号维度，但是亚奈奎斯特采样信号的结构并没有得到充分研究。本文针对线性调制基带信号的亚奈奎斯特采样，研究其信号恢复性能极限与算法。该问题中，原信号维度无法降低，因此亚奈奎斯特采样不可避免会带来信息损失，信号恢复也变成一个欠定线性问题。本文采用两种亚奈奎斯特采样方法对线性调制基带信号进行采样，分别研究了两种采样方法下的性能极限和信号恢复算法。首先，针对两种亚奈奎斯特采样方法，分别计算了采样序列之间的最小归一化欧氏距离，以此作为最优性能的指标。然后，在基带信号有限符号集的限制条件下，采用改进的时变维特比算法从亚奈奎斯特采样序列中恢复原信号。将仿真得到的亚奈奎斯特采样的误比特率与其性能的理论极限比较，并与奈奎斯特采样性能对比，验证了时变维特比算法在信号恢复问题中的优良性能。

关键词： 奈奎斯特采样定理；亚奈奎斯特采样；最小欧式距离；欠定线性问题；时变维特比算法    

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Benzene removal by nano magnetic particles under continuous condition from aqueous solutions

Amin Mohammad Mehdi,Bina Bijan,Majd Amir Masoud Samani,Pourzamani Hamidreza

《环境科学与工程前沿（英文）》 2014年 第8卷 第3期   页码 345-356 doi: 10.1007/s11783-013-0574-4

摘要： Benzene removal from aqueous solutions was evaluated using Fe O nano magnetic particles (NM) in continuous condition. A 4 factorial design including initial benzene concentration, NM dose, contact time and pH was investigated in 16 experiments (Taguchi OA design). The results indicated that all factors were significant and the optimum condition was: pH 8, NM dose of 2000 mg·L , benzene concentrations of 100 mg·L and contact time of 14 min. The maximum benzene uptake and distribution ratio in the optimum situation were 49.4 mg·g and 38.4 L·g , respectively. The nano particles were shown to capture 98.7% of the benzene in optimum batch condition and 94.5% in continuous condition. The isotherm data proved that the Brunauer-Emmett-Teller model fit more closely and produced an isotherm constant (b) less than one, indicating favorable adsorption. Regeneration studies verified that the benzene adsorbed by the NM could be easily desorbed by temperature, and thereby, NM can be employed repeatedly in water and wastewater management.

关键词： benzene     experimental design     Fe3O4     continues condition     thermal recycling    

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Overview of condition monitoring and operation control of electric power conversion systems in direct-drivewind turbines under faults

Shoudao HUANG, Xuan WU, Xiao LIU, Jian GAO, Yunze HE

《机械工程前沿（英文）》 2017年 第12卷 第3期   页码 281-302 doi: 10.1007/s11465-017-0442-1

摘要：

Electric power conversion system (EPCS), which consists of a generator and power converter, is one of the most important subsystems in a direct-drive wind turbine (DD-WT). However, this component accounts for the most failures (approximately 60% of the total number) in the entire DD-WT system according to statistical data. To improve the reliability of EPCSs and reduce the operation and maintenance cost of DD-WTs, numerous researchers have studied condition monitoring (CM) and fault diagnostics (FD). Numerous CM and FD techniques, which have respective advantages and disadvantages, have emerged. This paper provides an overview of the CM, FD, and operation control of EPCSs in DD-WTs under faults. After introducing the functional principle and structure of EPCS, this survey discusses the common failures in wind generators and power converters; briefly reviewed CM and FD methods and operation control of these generators and power converters under faults; and discussed the grid voltage faults related to EPCSs in DD-WTs. These theories and their related technical concepts are systematically discussed. Finally, predicted development trends are presented. The paper provides a valuable reference for developing service quality evaluation methods and fault operation control systems to achieve high-performance and high-intelligence DD-WTs.

关键词： direct-drive wind turbine     electric power conversion system     condition monitoring     fault diagnosis     operation control under faults     fault tolerance    

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Simulation of flow excursion and thermal siphon under natural circulation condition with lower pressure

WANG Jianjun, YANG Xingtuan, JIANG Shengyao

《能源前沿（英文）》 2008年 第2卷 第2期   页码 169-173 doi: 10.1007/s11708-008-0044-z

摘要： The simulation of flow excursion was conducted under HRTL-5 condition. The mechanism analysis and the simulation of thermal siphon process were also performed. The result shows that the computer code can be used to simulate the static instability of a natural circulation system and the simulation of flow excursion almost conforms to the experiment result.

关键词： HRTL-5     experiment     circulation     simulation     thermal    

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Study of two-phase flow regime identification in horizontal tube bundles under vertical upward cross-flowcondition using wavelet transform

HUANG Xinghua, WANG Li, JIA Feng

《能源前沿（英文）》 2008年 第2卷 第3期   页码 333-338 doi: 10.1007/s11708-008-0043-0

摘要： A wavelet-transform based approach for flow regime identification in horizontal tube bundles under vertical upward cross-flow condition was presented. Tests on two-phase flow pattern of R134a were conducted under low mass velocity and flow boiling conditions over ranges of mass flux 4–25 kg/ms, vapor quality 0.02–0.90. Time series of differential pressure fluctuations were measured and analyzed with discrete wavelet transform. Different time-scale characteristics in bubbly flow, churn flow and annular flow were analyzed. The wavelet energy distributions over scales were found to be appropriate for flow regime identification. Based on the wavelet energy distribution over characteristic scales, a criterion of flow regime identification was proposed. The comparison with experiment results show that it is feasible to use the discrete wavelet transform as the tool of flow regime identification in horizontal tube bundles under vertical upward cross-flow condition.

关键词： two-phase     discrete     appropriate     wavelet-transform     criterion    

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Optimization of urban bus operation frequency under common route condition with rail transit

Bin YU, Sijia REN, Enze WU, Yifan ZHOU, Yunpeng WANG

《工程管理前沿（英文）》 2017年 第4卷 第4期   页码 451-462 doi: 10.15302/J-FEM-2017036

摘要： The overlap of bus and rail transit routes is common in China. This overlap provides passengers multiple choices for one trip. However, the availability of multiple options would cause uncertainty in the travel distribution of passengers. Given that buses and rail transits are becoming increasingly common, this paper aims to present the overlapped operation condition of bus and rail transit using a bi-level model from the perspective of bus operators. Frequency optimization model is established in the upper-level model. A heuristic algorithm called shuffled complex evolution (SCE-UA) method is used to solve the established frequency optimization model, and three other heuristic methods are compared with SCE-UA. A lower-level Logit model based on Agent simulation is set for traffic mode split. Data on the transit system in Dalian city are chosen as an example to test the feasibility of the model and the algorithm. Results show that as the overlapped optimization of bus route and rail transit routes changed primary bus frequency, the use of SCE-UA to solve such problems has evident advantages and feasibility; furthermore, changed bus frequency would improve bus operations.

关键词： common route     bus operation frequency     bi-level model     Agent simulation     SCE-UA algorithm    

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Chemical reactions of oily sludge catalyzed by iron oxide under supercritical water gasification condition

《化学科学与工程前沿（英文）》 2022年 第16卷 第6期   页码 886-896 doi: 10.1007/s11705-021-2125-z

摘要： Supercritical water gasification is a promising technology in dealing with the degradation of hazardous waste, such as oily sludge, accompanied by the production of fuel gases. To evaluate the mechanism of Fe2O3 catalyst and the migration pathways of heteroatoms and to investigate the systems during the process, reactive force field molecular dynamics simulations are adopted. In terms of the catalytic mechanisms of Fe2O3, the surface lattice oxygen is consumed by small carbon fragments to produce CO and CO2, improving the catalytic performance of the cluster due to more unsaturated coordination Fe sites exposed. Lattice oxygen combines with •H radicals to form water molecules, improving the catalytic performance. Furthermore, the pathway of asphaltene degradation was revealed at an atomic level, as well as products. Moreover, the adsorption of hydroxyl radical on the S atom caused breakage of the two C–S bonds in turn, forming •HSO intermediate, so that the organic S element was fixed into the inorganic liquid phase. The heteroatom O was removed under the effects of supercritical water. Heavy metal particles presented in the oily sludge, such as iron in association with Fe2O3 catalyst, helped accelerate the degradation of asphaltenes.

关键词： oily sludge     SCWG     ReaxFF     Fe2O3     heteroatoms    

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Multi-Component Resource Recycling from Waste Light-Emitting Diode Under Hydrothermal Condition: Plastic

Yongliang Zhang,Lu Zhan,Zhenming Xu,

《工程（英文）》 doi: 10.1016/j.eng.2023.04.008

摘要： Light emitting diodes (LEDs) have accounted for most of the lighting market as the technology matures and costs continue to reduce. As a new type of e-waste, LED is a double-edged sword, as it contains not only precious and rare metals but also organic packaging materials. In previous studies, LED recycling focused on recovering precious and strategic metals while ignoring harmful substances such as organic packaging materials. Unlike crushing and other traditional methods, hydrothermal treatment can provide an environment-friendly process for decomposing packaging materials. This work developed a closed reaction vessel, where the degradation rate of plastic polyphthalamide (PPA) was close to 100%, with nano-TiO2 encapsulated in plastic PPA being efficiently recovered, while metals contained in LED were also recycled efficiently. Besides, the role of water in plastic PPA degradation that has been overlooked in current studies was explored and speculated in detail in this work. Environmental impact assessment revealed that the proposed recycling route for waste LED could significantly reduce the overall environmental impact compared to the currently published processes. Especially the developed method could reduce more than half the impact of global warming. Furthermore, this research provides a theoretical basis and a promising method for recycling other plastic-packaged e-waste devices, such as integrated circuits.

关键词： Waste LED     Hydrothermal treatment     Recycling     Plastic PPA degradation     Packaging materials    

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Frost heave and freezing processes of saturated rock with an open crack under different freezing conditions

Zhitao LV, Caichu XIA, Yuesong WANG, Ziliang LIN

《结构与土木工程前沿（英文）》 2020年 第14卷 第4期   页码 947-960 doi: 10.1007/s11709-020-0638-z

摘要： Frost heave experiments on saturated sandstone and tuff with an open crack are conducted under uniform and unidirectional freezing conditions. Frost heave of crack in sandstone with high permeability is more significant under uniform freezing condition than that under unidirectional freezing condition. However, frost heave of crack in tuff with low permeability is more significant under unidirectional freezing condition. To illustrate the reasons for this phenomenon, a numerical model on the freezing processes of saturated rock with an open crack considering the latent heat of pore water and water in crack is proposed and confirmed to be reliable. Numerical results show that a frozen shell that blocks the migration of water in crack to rock develops first in the outer part of the rock before the freezing of water in crack under uniform freezing condition. However, the migration path of water in crack to the unfrozen rock under freezing front exists under unidirectional freezing condition. The freezing process and permeability of rock together determine the migration of water in crack and lead to the different frost heave modes of crack for various permeable rocks under different freezing conditions. The frost heave modes of crack in rock with low or high permeability are similar under uniform freezing condition because water migration is blocked by a frozen shell and is irrelevant to rock permeability. For high permeability rock, the frost heave of crack will be weakened due to water migration under unidirectional freezing condition; however, the frost heave of crack would be more significant for low permeability rock because water migration is blocked under unidirectional freezing condition. Therefore, the freezing condition and rock permeability determine the frost heave of rock with crack together, and this should be concerned in cold regions engineering applications.

关键词： frost heave     rock with crack     freezing process     freezing condition     frost heave mode    

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Simulation of performance of intermediate fluid vaporizer under wide operation conditions

Bojie WANG, Wen WANG, Chao QI, Yiwu KUANG, Jiawei XU

《能源前沿（英文）》 2020年 第14卷 第3期   页码 452-462 doi: 10.1007/s11708-020-0681-4

摘要： The intermediate fluid vaporizer (IFV) is a typical vaporizer of liquefied natural gas (LNG), which in general consists of three shell-and-tube heat exchangers (an evaporator, a condenser, and a thermolator). LNG is heated by seawater and the intermediate fluid in these heat exchangers. A one-dimensional heat transfer model for IFV is established in this paper in order to investigate the influences of structure and operation parameters on the heat transfer performance. In the rated condition, it is suggested to reduce tube diameters appropriately to get a large total heat transfer coefficient and increase the tube number to ensure the sufficient heat transfer area. According to simulation results, although the IFV capacity is much larger than the simplified-IFV (SIFV) capacity, the mode of SIFV could be recommended in some low-load cases as well. In some cases at high loads exceeding the capacity of a single IFV, it is better to add an AAV or an SCV operating to the IFV than just to increase the mass flow rate of seawater in the IFV in LNG receiving terminals.

关键词： liquefied natural gas     intermediate fluid vapo-rizer     heat transfer performance     numerical simulation     extreme condition    

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Sufficient or insufficient: Assessment of the intended nationally determined contributions (INDCs) of

Ge GAO, Mo CHEN, Jiayu WANG, Kexin YANG, Yujiao XIAN, Xunpeng SHI, Ke WANG

《工程管理前沿（英文）》 2019年 第6卷 第1期   页码 19-37 doi: 10.1007/s42524-019-0007-6

摘要：

The recent Conference of the Parties of the United Nations Framework Convention on Climate Change has resulted in the submission of the Intended Nationally Determined Contributions (INDCs) of 190 countries. This study aims to provide an analysis of the ambitiousness and fairness of the mitigation components of the INDCs submitted by various parties. We use a unified framework to assess 23 INDCs that cover 50 countries, including European Union (EU)-28 countries as parties to the Convention, which represent 87.45% of the global greenhouse gas emissions in 2012. First, we transform initial INDC files into reported reduction targets. Second, we create four schemes and six scenarios to determine the required reduction effort, which considers each nation’s reduction responsibility, capacity, and potential, thereby reflecting their historical and current development status. Finally, we combine the reported reduction target and the required reduction effort to assess INDCs. Evaluation results of the 23 emitters indicate that 2 emitters (i.e., EU and Brazil) are rated as “sufficient,” 7 emitters (e.g., China, the United States, and Canada) are rated as “moderate,” and 14 emitters (e.g., India, Russia, and Japan) are rated as “insufficient.” Most pledges exhibit a considerable distance from representing a fair contribution.

关键词： Intended Nationally Determined Contributions     mitigation     responsibility     capacity     potential    

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Influence of site conditions on seismic design parameters for foundations as determined via nonlinear

Muhammad Tariq A. CHAUDHARY

《结构与土木工程前沿（英文）》 2021年 第15卷 第1期   页码 275-303 doi: 10.1007/s11709-021-0685-0

摘要： Site conditions, including geotechnical properties and the geological setting, influence the near-surface response of strata subjected to seismic excitation. The geotechnical parameters required for the design of foundations include mass density ( ), damping ratio ( ), shear wave velocity ( ), and soil shear modulus ( ). The values of the last three parameters are sensitive to the level of nonlinear strain induced in the strata due to seismic ground motion. In this study, the effect of variations in soil properties, such as plasticity index ( ), effective stress ( ), over consolidation ratio (OCR), impedance contrast ratio ( ) between the bedrock and the overlying strata, and depth of soil strata over bedrock ( ), on seismic design parameters ( , , and ) was investigated for National Earthquake Hazards Reduction Program (NEHRP) site classes C and D, through 1D nonlinear seismic site response analysis. The Morris one-at-a-time (OAT) sensitivity analysis indicated that , , and were significantly influenced by variations in , while affected more than it affected and . However, the influence of on these parameters was less significant. It was also found that variations in soil properties influenced seismic design parameters in soil type D more significantly than in soil type C. Predictive relationships for , , and were derived based on the 1D seismic site response analysis and sensitivity analysis results. The , , and values obtained from the analysis were compared with the corresponding values in NEHRP to determine the similarities and differences between the two sets of values. The need to incorporate and in the metrics for determining , , and for the seismic design of foundations was highlighted.

关键词： site effects     1D seismic site response analysis     sensitivity analysis     foundations     shear wave velocity     soil shear modulus    

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A review of condition-based maintenance: Its prognostic and operational aspects

Yanrong LI, Shizhe PENG, Yanting LI, Wei JIANG

《工程管理前沿（英文）》 2020年 第7卷 第3期   页码 323-334 doi: 10.1007/s42524-020-0121-5

摘要： Condition-based maintenance (CBM) detects early signs of failure and dictates when maintenance should be performed based on the actual condition of a system. In this paper, we first review some of the recent research on CBM under various physical structures and signal data. Then, we summarize several kinds of prognostic models that use monitoring information to estimate the reliability of complex systems or products. Monitoring information also facilitates operational decisions in production planning, spare parts management, reliability improvement, and prognostics and health management. Finally, we suggest some research opportunities for the reliability and operations management communities to fill the research gap between these two fields.

关键词： condition-based maintenance     prognostics     operational decision-making     reliability    

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标题 作者 时间 类型 操作

Non-convex sparse optimization-based impact force identification with limited vibration measurements

期刊论文

A dynamic stiffness-based framework for harmonic input estimation and response reconstruction considering damage

Yixian LI; Limin SUN; Wang ZHU; Wei ZHANG

期刊论文

亚奈奎斯特采样的数据恢复：性能极限与恢复算法

罗茜倩,张朝阳

期刊论文

Benzene removal by nano magnetic particles under continuous condition from aqueous solutions

Amin Mohammad Mehdi,Bina Bijan,Majd Amir Masoud Samani,Pourzamani Hamidreza

期刊论文

Overview of condition monitoring and operation control of electric power conversion systems in direct-drivewind turbines under faults

Shoudao HUANG, Xuan WU, Xiao LIU, Jian GAO, Yunze HE

期刊论文

Simulation of flow excursion and thermal siphon under natural circulation condition with lower pressure

WANG Jianjun, YANG Xingtuan, JIANG Shengyao

期刊论文

Study of two-phase flow regime identification in horizontal tube bundles under vertical upward cross-flowcondition using wavelet transform

HUANG Xinghua, WANG Li, JIA Feng

期刊论文

Optimization of urban bus operation frequency under common route condition with rail transit

Bin YU, Sijia REN, Enze WU, Yifan ZHOU, Yunpeng WANG

期刊论文

Chemical reactions of oily sludge catalyzed by iron oxide under supercritical water gasification condition

期刊论文

Multi-Component Resource Recycling from Waste Light-Emitting Diode Under Hydrothermal Condition: Plastic

Yongliang Zhang,Lu Zhan,Zhenming Xu,

期刊论文

Frost heave and freezing processes of saturated rock with an open crack under different freezing conditions

Zhitao LV, Caichu XIA, Yuesong WANG, Ziliang LIN

期刊论文

Simulation of performance of intermediate fluid vaporizer under wide operation conditions

Bojie WANG, Wen WANG, Chao QI, Yiwu KUANG, Jiawei XU

期刊论文

Sufficient or insufficient: Assessment of the intended nationally determined contributions (INDCs) of

Ge GAO, Mo CHEN, Jiayu WANG, Kexin YANG, Yujiao XIAN, Xunpeng SHI, Ke WANG

期刊论文

Influence of site conditions on seismic design parameters for foundations as determined via nonlinear

Muhammad Tariq A. CHAUDHARY

期刊论文

A review of condition-based maintenance: Its prognostic and operational aspects

Yanrong LI, Shizhe PENG, Yanting LI, Wei JIANG

期刊论文