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The Immense Impact of Reverse Edges on Large Hierarchical Networks

Haosen Cao,Bin-Bin Hu,Xiaoyu Mo,Duxin Chen,Jianxi Gao,Ye Yuan,Guanrong Chen,Tamás Vicsek,Xiaohong Guan,Hai-Tao Zhang,

《工程（英文）》 doi: 10.1016/j.eng.2023.06.011

摘要： Hierarchical networks are frequently encountered in animal groups, gene networks, and artificial engineering systems such as multiple robots, unmanned vehicle systems, smart grids, wind farm networks, and so forth. The structure of a large directed hierarchical network is often strongly influenced by reverse edges from lower- to higher- level nodes, such as lagging birds’ howl in a flock or the opinions of lower-level individuals feeding back to higher-level ones in a social group. This study reveals that, for most large-scale real hierarchical networks, the majority of the reverse edges do not affect the synchronization process of the entire network; the synchronization process is influenced only by a small part of these reverse edges along specific paths. More surprisingly, a single effective reverse edge can slow down the synchronization of a huge hierarchical network by over 60%. The effect of such edges depends not on the network size but only on the average in-degree of the involved subnetwork. The overwhelming majority of active reverse edges turn out to have some kind of “bunching” effect on the information flows of hierarchical networks, which slows down synchronization processes. This finding refines the current understanding of the role of reverse edges in many natural, social, and engineering hierarchical networks, which might be beneficial for precisely tuning the synchronization rhythms of these networks. Our study also proposes an effective way to attack a hierarchical network by adding a malicious reverse edge to it and provides some guidance for protecting a network by screening out the specific small proportion of vulnerable nodes.

关键词： Synchronizability     Large hierarchical networks     Reverse edges     Information flows     Complex networks    

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Erratum to: Soft-HGRNs: soft hierarchical graph recurrent networks for multi-agent partially observable

Yixiang REN, Zhenhui YE, Yining CHEN, Xiaohong JIANG, Guanghua SONG

《信息与电子工程前沿（英文）》 2023年 第24卷 第3期   页码 480-480 doi: 10.1631/FITEE.22e0073

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Deep convolutional tree-inspired network: a decision-tree-structured neural network for hierarchical

《机械工程前沿（英文）》 2021年 第16卷 第4期   页码 814-828 doi: 10.1007/s11465-021-0650-6

摘要： The fault diagnosis of bearings is crucial in ensuring the reliability of rotating machinery. Deep neural networks have provided unprecedented opportunities to condition monitoring from a new perspective due to the powerful ability in learning fault-related knowledge. However, the inexplicability and low generalization ability of fault diagnosis models still bar them from the application. To address this issue, this paper explores a decision-tree-structured neural network, that is, the deep convolutional tree-inspired network (DCTN), for the hierarchical fault diagnosis of bearings. The proposed model effectively integrates the advantages of convolutional neural network (CNN) and decision tree methods by rebuilding the output decision layer of CNN according to the hierarchical structural characteristics of the decision tree, which is by no means a simple combination of the two models. The proposed DCTN model has unique advantages in 1) the hierarchical structure that can support more accuracy and comprehensive fault diagnosis, 2) the better interpretability of the model output with hierarchical decision making, and 3) more powerful generalization capabilities for the samples across fault severities. The multiclass fault diagnosis case and cross-severity fault diagnosis case are executed on a multicondition aeronautical bearing test rig. Experimental results can fully demonstrate the feasibility and superiority of the proposed method.

关键词： bearing     cross-severity fault diagnosis     hierarchical fault diagnosis     convolutional neural network     decision tree    

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光纤通信技术发展现状与展望

谈仲纬,吕超

《中国工程科学》 2020年 第22卷 第3期   页码 100-107 doi: 10.15302/J-SSCAE-2020.03.016

摘要：

作为激光技术的重要应用，光纤通信技术是搭建现代通信网络的重要桥梁。随着物联网、大数据、云计算、虚拟现实和人工智能等新兴技术的涌现，信息传递需求与日俱增，这对光纤通信技术的发展提出了更高要求。本文在系统梳理光纤通信技术国内外发展现状的基础上，分析了在具体场景应用中面临的问题与挑战，研判了未来光纤通信技术发展的方向。经研究分析，激光通信技术在超大容量光纤通信系统中面临的挑战可从发射功率增加、光放大器带宽增加、低传输损耗光纤以及空分复用相关技术研究等方面入手探讨解决思路；同时结合现实应用情况，本文对面向其他场景的光纤通信系统成本困境的解决进行了思考。总体而言，光纤通信技术将朝着超大容量、智能化、集成化的方向不断演进，未来期望可以实现智能化网络参数监测和超长距离、超大容量信息传输，并且随着集成技术和光通信器件的不断进步，必将推动整个光纤通信行业的高性能、低成本发展。

关键词： 光纤通信     光网络     超大容量     集成     智能化    

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Combined reticular blind drainage and vertical hierarchical drainage system for landfills located in

Wenjing LU,Zhonge FU,Yan ZHAO

《环境科学与工程前沿（英文）》 2016年 第10卷 第1期   页码 177-184 doi: 10.1007/s11783-014-0710-9

摘要： A novel water control technology that combines the features of a reticular blind drainage system and a vertical hierarchical drainage system is developed and applied in the Yanziyan Sanitary Landfill, which is located at an area (Loudi City, Hunan Province, China) with high rainfall and high groundwater level. The reticular blind drain system, which was installed on the bottom and side walls of the landfill site, can conveniently guide the flow of groundwater out of the site while preventing a disorganized flow of groundwater. The vertical hierarchical drainage system was installed to separate rainfall water and leachate in the landfill site, thus efficiently reducing the pressure of leachate treatment. The whole drainage system plays a key role in foundation stabilization by seepage control and separation and in the instant drainage of rainfall water. The leachate reduction efficiency of the drainage technology was calculated in terms of leachate production before (336519 m ) and after (29664 m ) technology application. Over 90% of leachate derived from rainfall water and groundwater inflow was avoided upon installation of the vertical hierarchical drainage and reticular blind drainage systems. The technology can thus be popularized and applied for water control in landfills located in areas with high rainfall and high groundwater level. The proposed technology can be used to alleviate the pressure of leachate treatment and to reduce the risk of instability.

关键词： landfill     reticular blind drain     vertical hierarchical drain     guidance and drainage     impermeable layer    

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基于级联聚合算法下的布尔网络最优单点摄动 Research Articles

Jin-feng PAN, Min MENG

《信息与电子工程前沿（英文）》 2020年 第21卷 第2期   页码 294-303 doi: 10.1631/FITEE.1900411

摘要： 研究级联聚合算法分割下的大型布尔网络最优单点摄动问题；最大化期望吸引子吸引域，同时最小化非期望吸引子吸引域。首先，通过级联聚合算法给出一个在单点摄动下保持期望吸引子不变的充要条件。其次，提出一个判定是否出现新吸引子的算法。然后，提出另一算法给出单点摄动下吸引子吸引域的大小变化。最后，将本文理论应用于寻找T细胞受体网络的最优单点摄动问题。

关键词： 大型布尔网络；吸引子；级联聚合算法；单点摄动    

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Effect of hierarchical ZSM-5 zeolite crystal size on diffusion and catalytic performance of n-heptane

Shuman Xu, Xiaoxiao Zhang, Dangguo Cheng, Fengqiu Chen, Xiaohong Ren

《化学科学与工程前沿（英文）》 2018年 第12卷 第4期   页码 780-789 doi: 10.1007/s11705-018-1733-8

摘要： Hierarchical ZSM-5 zeolite aggregates with different sizes of nanocrystals were synthesized using different amounts of the mesoporogen 3-aminopropyltriethoxysilane. The effect of the crystal size on the catalytic cracking of -heptane was investigated and the Thiele modulus and effectiveness factor were used to determine the reaction rate-limiting step. The crystal size affected the textual properties of the catalysts but not the acidic properties of the catalysts. The reaction rate was first order with respect to the -heptane concentration. Cracking over hierarchical zeolites with nanocrystal sizes larger than about 50 nm took place under transition-limiting conditions, whereas the reaction over hierarchical zeolites with nanocrystal sizes of 15 or 30 nm proceeded under reaction control conditions. Hierarchical ZSM-5 zeolite aggregates with smaller nanocrystals had better selectivity for light olefins which can be ascribed to the shorter diffusion path lengths and lower diffusion resistance in these catalysts. Furthermore, these catalysts had lower coking levels which can be attributed to the substantial number of mesopores which prevent the formation of coke precursors.

关键词： hierarchical ZSM-5     crystal size     catalytic cracking     Thiele modulus     effectiveness factor    

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基于层次优化的图像网格化方法

Hao XIE,Ruo-feng TONG

《信息与电子工程前沿（英文）》 2016年 第17卷 第1期   页码 32-40 doi: 10.1631/FITEE.1500171

摘要：

矢量图形作为光栅图像的一种几何表示形式，具有许多优点，例如，定义独立性和编辑功能。将栅格图像转换为矢量图形的一种流行方法是图像网格划分，其目的是找到一个网格以尽可能忠实地表示图像。对于传统的网格划分算法，问题的症结主要在于目标的高非线性度和非平滑度，这使得很难找到理想的最优解。为了改善这种情况，我们提出了一种层次优化算法，解决了从较粗级别到较细级别的问题，并为每个级别提供了其较粗的提升的初始化功能。为了进一步简化问题，将原始的非凸问题转换为线性最小二乘，从而变成凸的，这使问题更容易解决。字典学习框架用于将几何和拓扑完美地结合在一起。然后采用交替方案来求解两个部分。实验表明，对于大多数图像，该算法运行速度快，效果优于现有图像。

关键词： 图像网格化；层次优化；凸化    

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Facile synthesis of hierarchical flower-like Ag/Cu

Mengyun Wang, Shengbo Zhang, Mei Li, Aiguo Han, Xinli Zhu, Qingfeng Ge, Jinyu Han, Hua Wang

《化学科学与工程前沿（英文）》 2020年 第14卷 第5期   页码 813-823 doi: 10.1007/s11705-019-1854-8

摘要： Novel, hierarchical, flower-like Ag/Cu O and Au/Cu O nanostructures were successfully fabricated and applied as efficient electrocatalysts for the electrochemical reduction of CO . Cu O nanospheres with a uniform size of ~180 nm were initially synthesized. Thereafter, Cu O was used as a sacrificial template to prepare a series of Ag/Cu O composites through galvanic replacement. By varying the Ag/Cu atomic ratio, Ag /Cu O, having a hierarchical, flower-like nanostructure with intersecting Ag nanoflakes encompassing an inner Cu O sphere, was prepared. The as-prepared Ag /Cu O samples presented higher Faradaic efficiencies (FE) for CO and relatively suppressed H evolution than the parent Cu O nanospheres due to the combination of Ag with Cu O in the former. Notably, the highest CO evolution rate was achieved with Ag /Cu O due to the larger electroactive surface area furnished by the hierarchical structure. The same hierarchical flower-like structure was also obtained for the Au /Cu O composite, where the FE (10%) was even higher than that of Ag /Cu O. Importantly, the results reveal that Ag /Cu O and Au /Cu O both exhibit remarkably improved stability relative to Cu O. This study presents a facile method of developing hierarchical metal-oxide composites as efficient and stable electrocatalysts for the electrochemical reduction of CO .

关键词： bimetallic nanostructure     hierarchical metal/oxide nanomaterial     galvanic replacement     electrochemical reduction of CO2    

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Hierarchical parameter estimation of DFIG and drive train system in a wind turbine generator

Xueping PAN, Ping JU, Feng WU, Yuqing JIN

《机械工程前沿（英文）》 2017年 第12卷 第3期   页码 367-376 doi: 10.1007/s11465-017-0429-y

摘要：

A new hierarchical parameter estimation method for doubly fed induction generator (DFIG) and drive train system in a wind turbine generator (WTG) is proposed in this paper. Firstly, the parameters of the DFIG and the drive train are estimated locally under different types of disturbances. Secondly, a coordination estimation method is further applied to identify the parameters of the DFIG and the drive train simultaneously with the purpose of attaining the global optimal estimation results. The main benefit of the proposed scheme is the improved estimation accuracy. Estimation results confirm the applicability of the proposed estimation technique.

关键词： wind turbine generator     DFIG     drive train system     hierarchical parameter estimation method     trajectory sensitivity technique    

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Erratum to: Synthesis of hierarchical nanohybrid CNT@Ni-PS and its applications in enhancing the tribological

《化学科学与工程前沿（英文）》 2022年 第16卷 第10期   页码 1530-1530 doi: 10.1007/s11705-022-2240-5

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Novel hierarchical yolk-shell

Xiqing Luo, Miaomiao Jiang, Kun Shi, Zhangxian Chen, Zeheng Yang, Weixin Zhang

《化学科学与工程前沿（英文）》 2021年 第15卷 第5期   页码 1322-1331 doi: 10.1007/s11705-021-2036-z

摘要： For high performance supercapacitors, novel hierarchical yolk-shell -Ni(OH) /Mn O microspheres were controllably synthesized using a facile two-step method based on the solvothermal treatment. The unique -Ni(OH) based yolk-shell microstructures decorated with numerous interconnected nanosheets and the hetero-composition features can synergistically enhance reactive site exposure and electron conduction within the microspheres, facilitate charge transfer between electrolyte and electrode materials, and release structural stress during OH chemisorption/desorption. Moreover, the Mn O sediments distributed over the -Ni(OH) microspheres can serve as an effective protective layer for electrochemical reactions. Consequently, when tested in 1 mol·L KOH aqueous electrolyte for supercapacitors, the yolk-shell -Ni(OH) /Mn O microspheres exhibited a considerably high specific capacitance of 2228.6 F·g at 1 A·g and an impressive capacitance retention of 77.7% after 3000 cycles at 10 A·g . The proposed -Ni(OH) /Mn O microspheres with hetero-composition and unique hierarchical yolk-shell microstructures are highly promising to be used as electrode materials in supercapacitors and other energy storage devices.

关键词：    

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Hierarchical fractal structure of perfect single-layer graphene

T. Zhang, K. Ding

《机械工程前沿（英文）》 2013年 第8卷 第4期   页码 371-382 doi: 10.1007/s11465-013-0279-1

摘要：

The atomic lattice structure of perfect single-layer graphene that can actually be regarded as a kind of hierarchical fractal structure from the perspective of fractal geometry was studied for the first time. Three novel and special discoveries on hierarchical fractal structure and sets were unveiled upon examination of the regular crystal lattices of the single-layer graphene. The interior fractal-type structure was discovered to be the fifth space-filling curve from physical realm. Two efficient methods for calculating the fractal dimension of this fresh member was also provided. The outer boundary curve had a fractal dimension equal to one, and a multi-fractal structure from a naturally existing material was found for the first time. A series of strict self-similar hexagons comprised a rotating fractal set. These hexagons slewed at a constant counterclockwise angle of 19.1° when observed from one level to the next higher level. From the perspective of fractal geometry, these pioneering discoveries added three new members to the existing regular fractal structures and sets. A fundamental example of a multi-fractal structure was also presented.

关键词： hierarchical fractal structure     fractal dimension     the fifth space-filling curve     multi-fractal structure    

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Postsynthesis of hierarchical core/shell ZSM-5 as an efficient catalyst in ketalation and acetalization

Peng Luo, Yejun Guan, Hao Xu, Mingyuan He, Peng Wu

《化学科学与工程前沿（英文）》 2020年 第14卷 第2期   页码 258-266 doi: 10.1007/s11705-019-1878-0

摘要： Hierarchical core/shell Zeolite Socony Mobil-five (ZSM-5) zeolite was hydrothermally postsythesized in the solution of NaOH and diammonium surfactant via a dissolution-reassembly strategy. The silica and alumina species were firstly dissolved partially from the bulky ZSM-5 crystals and then were reassembled into the MFI-type nanosheets with the structure-directing effect of diammonium surfactant, attaching to the out-surface of ZSM-5 core crystals. The mesopores thus were generated in both the core and shell part, giving rise to a micropore/mesopore composite material. The micropore volume and the acidity of the resultant hybrid were well-preserved during this recrystallization process. Possessing the multiple mesopores and enlarged external surface area, the core/shell ZSM-5 zeolite exhibited higher activity in the ketalation and acetalization reactions involving bulky molecules in comparison to the pristine ZSM-5.

关键词： core/shell ZSM-5     in situ recrystallization     mesopore     ketalation and acetalization reactions    

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Hierarchical ZSM-5 zeolite with radial mesopores: Preparation, formation mechanism and application for

Darui Wang, Hongmin Sun, Wei Liu, Zhenhao Shen, Weimin Yang

《化学科学与工程前沿（英文）》 2020年 第14卷 第2期   页码 248-257 doi: 10.1007/s11705-019-1853-9

摘要： Hierarchical ZSM-5 zeolite with radial mesopores is controllably synthesized using piperidine in a NaOH solution. The piperidine molecules enter the zeolite micropores and protect the zeolite framework from extensive desilication. The areas containing fewer aluminum atoms contain fewer piperidine protectant molecules and so they dissolve first. Small amounts of mesopores are then gradually generated in areas with more aluminum atoms and more piperidine protectant. In this manner, radial mesopores are formed in the ZSM-5 zeolite with a maximal preservation of the micropores and active sites. The optimal hierarchical ZSM-5 zeolite, prepared with a molar ratio of piperidine to zeolite of 0.03, had a mesopore surface area of 136 m ·g and a solid yield of 80%. The incorporation of the radial mesopores results in micropores that are interconnected which shortened the average diffusion path length. Compared to the parent zeolite, the hierarchical ZSM-5 zeolite possesses more accessible acid sites and has a higher catalytic activity and a longer lifetime for the alkylation of benzene.

关键词： hierarchical ZSM-5 zeolite     protective desilication     piperidine     radial mesopores     benzene alkylation    

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标题 作者 时间 类型 操作

The Immense Impact of Reverse Edges on Large Hierarchical Networks

Haosen Cao,Bin-Bin Hu,Xiaoyu Mo,Duxin Chen,Jianxi Gao,Ye Yuan,Guanrong Chen,Tamás Vicsek,Xiaohong Guan,Hai-Tao Zhang,

期刊论文

Erratum to: Soft-HGRNs: soft hierarchical graph recurrent networks for multi-agent partially observable

Yixiang REN, Zhenhui YE, Yining CHEN, Xiaohong JIANG, Guanghua SONG

期刊论文

Deep convolutional tree-inspired network: a decision-tree-structured neural network for hierarchical

期刊论文

光纤通信技术发展现状与展望

谈仲纬,吕超

期刊论文

Combined reticular blind drainage and vertical hierarchical drainage system for landfills located in

Wenjing LU,Zhonge FU,Yan ZHAO

期刊论文

基于级联聚合算法下的布尔网络最优单点摄动

Jin-feng PAN, Min MENG

期刊论文

Effect of hierarchical ZSM-5 zeolite crystal size on diffusion and catalytic performance of n-heptane

Shuman Xu, Xiaoxiao Zhang, Dangguo Cheng, Fengqiu Chen, Xiaohong Ren

期刊论文

基于层次优化的图像网格化方法

Hao XIE,Ruo-feng TONG

期刊论文

Facile synthesis of hierarchical flower-like Ag/Cu

Mengyun Wang, Shengbo Zhang, Mei Li, Aiguo Han, Xinli Zhu, Qingfeng Ge, Jinyu Han, Hua Wang

期刊论文

Hierarchical parameter estimation of DFIG and drive train system in a wind turbine generator

Xueping PAN, Ping JU, Feng WU, Yuqing JIN

期刊论文

Erratum to: Synthesis of hierarchical nanohybrid CNT@Ni-PS and its applications in enhancing the tribological

期刊论文

Novel hierarchical yolk-shell

Xiqing Luo, Miaomiao Jiang, Kun Shi, Zhangxian Chen, Zeheng Yang, Weixin Zhang

期刊论文

Hierarchical fractal structure of perfect single-layer graphene

T. Zhang, K. Ding

期刊论文

Postsynthesis of hierarchical core/shell ZSM-5 as an efficient catalyst in ketalation and acetalization

Peng Luo, Yejun Guan, Hao Xu, Mingyuan He, Peng Wu

期刊论文

Hierarchical ZSM-5 zeolite with radial mesopores: Preparation, formation mechanism and application for

Darui Wang, Hongmin Sun, Wei Liu, Zhenhao Shen, Weimin Yang

期刊论文