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Mechanical design and analysis of a novel variable stiffness actuator with symmetrical pivot adjustment

《机械工程前沿（英文）》 2021年 第16卷 第4期   页码 711-725 doi: 10.1007/s11465-021-0647-1

摘要： The safety of human–robot interaction is an essential requirement for designing collaborative robotics. Thus, this paper aims to design a novel variable stiffness actuator (VSA) that can provide safer physical human–robot interaction for collaborative robotics. VSA follows the idea of modular design, mainly including a variable stiffness module and a drive module. The variable stiffness module transmits the motion from the drive module in a roundabout manner, making the modularization of VSA possible. As the key component of the variable stiffness module, a stiffness adjustment mechanism with a symmetrical structure is applied to change the positions of a pair of pivots in two levers linearly and simultaneously, which can eliminate the additional bending moment caused by the asymmetric structure. The design of the double-deck grooves in the lever allows the pivot to move freely in the groove, avoiding the geometric constraint between the parts. Consequently, the VSA stiffness can change from zero to infinity as the pivot moves from one end of the groove to the other. To facilitate building a manipulator in the future, an expandable electrical system with a distributed structure is also proposed. Stiffness calibration and control experiments are performed to evaluate the physical performance of the designed VSA. Experiment results show that the VSA stiffness is close to the theoretical design stiffness. Furthermore, the VSA with a proportional–derivative feedback plus feedforward controller exhibits a fast response for stiffness regulation and a good performance for position tracking.

关键词： variable stiffness actuator     variable stiffness module     drive module     symmetrical structure     double-deck grooves     expandable electrical system    

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Different manipulation mode analysis of a radial symmetrical hexapod robot with leg–arm integration

《机械工程前沿（英文）》 2022年 第17卷 第1期   页码 8-8 doi: 10.1007/s11465-021-0664-0

摘要： With the widespread application of legged robot in various fields, the demand for a robot with high locomotion and manipulation ability is increasing. Adding an extra arm is a useful but general method for a legged robot to obtain manipulation ability. Hence, this paper proposes a novel hexapod robot with two integrated leg–arm limbs that obtain dexterous manipulation functions besides locomotion ability without adding an extra arm. The manipulation modes can be divided into coordinated manipulation condition and single-limb manipulation condition. The former condition mainly includes fixed coordinated clamping case and fixed coordinated shearing case. For the fixed coordinated clamping case, the degrees of freedom (DOFs) analysis of equivalent parallel mechanism by using screw theory and the constraint equation of two integrated limbs are established. For the fixed coordinated shearing case, the coordinated working space is determined, and an ideal coordinated manipulation ball is presented to guide the coordinated shearing task. In addition, the constraint analysis of two adjacent integrated limbs is performed. Then, mobile manipulation with one integrated leg–arm limb while using pentapod gait is discussed as the single-limb manipulation condition, including gait switching analysis between hexapod gait and pentapod gait, different pentapod gaits analysis, and a complex six-DOF manipulation while walking. Corresponding experiments are implemented, including clamping tasks with two integrated limbs, coordinated shearing task by using two integrated limbs, and mobile manipulation with pentapod gait. This robot provides a new approach to building a multifunctional locomotion platform.

关键词： leg–arm integration     hexapod robot     fixed coordinated manipulation     mobile manipulation    

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Fracture behavior of two non-symmetrical collinear cracks emanating from an elliptical hole in a piezoelectric

Junhong GUO, Zixing LU

《机械工程前沿（英文）》 2011年 第6卷 第3期   页码 296-300 doi: 10.1007/s11465-011-0236-9

摘要：

Based on the Stroh-type formalism and the technique of conformal mapping, the problem of two non-symmetrical collinear cracks emanating from an elliptical hole in a piezoelectric solid is investigated under remotely uniform in-plane electric loading and anti-plane mechanical loading, which allowed us to take the electric field inside the hole and cracks into account. The analytical solutions of the field intensity factors and the energy release rate are presented in closed-form, which includes the extreme cases for an impermeable crack and a permeable crack. Numerical results are then presented to reveal the effects of geometrical parameters, crack permeability and combined mechanical and electric loadings on the energy release rate.

关键词： piezoelectric materials     elliptical hole     semi-permeable crack     energy release rate     analytic solution    

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电力系统中对称和/或不对称故障的限流器阻抗优化新方法 None

Mahmoud MODARESI, Hamid LESANI

《信息与电子工程前沿（英文）》 2018年 第19卷 第2期   页码 297-307 doi: 10.1631/FITEE.1601689

摘要： 为给电力网络设计者选择故障限流器（fault current limiters，FCLs）的阻抗类型和阻值，提出一种基于其在网络中的位置计算最佳FCL阻值的新方法。由于阻抗的复杂性，需同时考虑FCL阻抗实部和虚部的代价。FCL阻抗优化的目标函数，是以最小化代价最大限度减少故障电流。虽然最佳FCL阻抗值的计算受其在网络中位置的影响，但选取FCL位置的方法并非本文重点。该FCL阻抗优化方法可用于任何具有对称和/或不对称故障的网络。以一个14总线IEEE网络为例解释该过程。该网络采用的最优FCL阻抗是同时考虑FCL阻抗实部和虚部的大范围代价计算得到的。

关键词： 故障限流器（FCL）；FCL阻抗；短路电流；故障电流；电力系统    

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Influence of pore structure on biologically activated carbon performance and biofilm microbial characteristics

《环境科学与工程前沿（英文）》 2021年 第15卷 第6期 doi: 10.1007/s11783-021-1419-1

摘要：

• Pore structure affects biologically activated carbon performance.

关键词： Granular activated carbon     Biologically activated carbon filter     Bacterial community structure     Pore structure    

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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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Floating forest: A novel breakwater-windbreak structure against wind and wave hazards

《结构与土木工程前沿（英文）》 2021年 第15卷 第5期   页码 1111-1127 doi: 10.1007/s11709-021-0757-1

摘要： A novel floating breakwater-windbreak structure (floating forest) has been designed for the protection of vulnerable coastal areas from extreme wind and wave loadings during storm conditions. The modular arch-shaped concrete structure is positioned perpendicularly to the direction of the prevailing wave and wind. The structure below the water surface acts as a porous breakwater with wave scattering capability. An array of tubular columns on the sloping deck of the breakwater act as an artificial forest-type windbreak. A feasibility study involving hydrodynamic and aerodynamic analyses has been performed, focusing on its capability in reducing wave heights and wind speeds in the lee side. The study shows that the proposed 1 km long floating forest is able to shelter a lee area that stretches up to 600 m, with 40%–60% wave energy reduction and 10%–80% peak wind speed reduction.

关键词： floating structure     breakwater     windbreak     hydrodynamic     CFD    

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Bicontinuous porous membranes with micro-nano composite structure using a facile atomization-assisted

《化学科学与工程前沿（英文）》 2022年 第16卷 第8期   页码 1268-1280 doi: 10.1007/s11705-022-2143-5

摘要： The micro-nano composite structure can endow separation membranes with special surface properties, but it often has the problems of inefficient preparation process and poor structural stability. In this work, a novel atomization-assisted nonsolvent induced phase separation method, which is also highly efficient and very simple, has been developed. By using this method, a bicontinuous porous microfiltration membrane with robust micro-nano composite structure was obtained via commercially available polymers of polyacrylonitrile and polyvinylpyrrolidone. The formation mechanism of the micro-nano composite structure was proposed. The microphase separation of polyacrylonitrile and polyvinylpyrrolidone components during the atomization pretreatment process and the hydrogen bonding between polyacrylonitrile and polyvinylpyrrolidone molecules should have resulted in the nano-protrusions on the membrane skeleton. The membrane exhibits superhydrophilicity in air and superoleophobicity underwater. The membrane can separate both surfactant-free and surfactant-stabilized oil-in-water emulsions with high separation efficiency and permeation flux. With excellent antifouling property and robust microstructure, the membrane can easily be recycled for long-term separation. Furthermore, the scale-up verification from laboratory preparation to continuous production has been achieved. The simple, efficient, cost-effective preparation method and excellent membrane properties indicate the great potential of the developed membranes in practical applications.

关键词： atomization     nonsolvent induced phase separation     bicontinuous porous structure     micro-nano composite structure     oil-water separation    

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Smart optical-fiber structure monitoring based on granular computing

Guan LU, Dakai LIANG,

《机械工程前沿（英文）》 2009年 第4卷 第4期   页码 462-465 doi: 10.1007/s11465-009-0073-2

摘要： Using an optic fiber self-diagnosing system in health monitoring has become an important direction of smart materials and structure research. The buried optic fiber sensor can be used to test the parameters of the composite material. The granular computing method can reach the requirement of damage detection by analyzing digital signals and character signals of the smart structure at the same time. The paper investigates an optic fiber smart layer and presents a method for realizing optic fiber smart structure monitoring and damage detection by using granular computing. After the analysis, it is presumed that optic fiber smart structure monitoring based on granular computation can identify the damage from complex signals.

关键词： smart material and structure     GrC     optical fiber sensor     rough set     clustering algorithm    

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Automated classification of civil structure defects based on convolutional neural network

Pierclaudio SAVINO, Francesco TONDOLO

《结构与土木工程前沿（英文）》 2021年 第15卷 第2期   页码 305-317 doi: 10.1007/s11709-021-0725-9

摘要： Today, the most commonly used civil infrastructure inspection method is based on a visual assessment conducted by certified inspectors following prescribed protocols. However, the increase in aggressive environmental and load conditions, coupled with the achievement of many structures of the life-cycle end, has highlighted the need to automate damage identification and satisfy the number of structures that need to be inspected. To overcome this challenge, this paper presents a method for automating concrete damage classification using a deep convolutional neural network. The convolutional neural network was designed after an experimental investigation of a wide number of pretrained networks, applying the transfer-learning technique. Training and validation were conducted using a database built with 1352 images balanced between “undamaged”, “cracked”, and “delaminated” concrete surfaces. To increase the network robustness compared to images in real-world situations, different image configurations have been collected from the Internet and on-field bridge inspections. The GoogLeNet model, with the highest validation accuracy of approximately 94%, was selected as the most suitable network for concrete damage classification. The results confirm that the proposed model can correctly classify images from real concrete surfaces of bridges, tunnels, and pavement, resulting in an effective alternative to the current visual inspection techniques.

关键词： concrete structure     infrastructures     visual inspection     convolutional neural network     artificial intelligence    

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Catalyst particle shapes and pore structure engineering for hydrodesulfurization and hydrodenitrogenation

《化学科学与工程前沿（英文）》 2022年 第16卷 第6期   页码 897-908 doi: 10.1007/s11705-021-2127-x

摘要： Catalyst particle shapes and pore structure engineering are crucial for alleviating internal diffusion limitations in the hydrodesulfurization (HDS)/hydrodenitrogenation (HDN) of gas oil. The effects of catalyst particle shapes (sphere, cylinder, trilobe, and tetralobe) and pore structures (pore diameter and porosity) on HDS/HDN performance at the particle scale are investigated via mathematical modeling. The relationship between particle shape and effectiveness factor is first established, and the specific surface areas of different catalyst particles show a positive correlation with the average HDS/HDN reaction rates. The catalyst particle shapes primarily alter the average HDS/HDN reaction rate to adjust the HDS/HDN effectiveness factor. An optimal average HDS/HDN reaction rate exists as the catalyst pore diameter and porosity increase, and this optimum value indicates a tradeoff between diffusion and reaction. In contrast to catalyst particle shapes, the catalyst pore diameter and the porosity of catalyst particles primarily alter the surface HDS/HDN reaction rate to adjust the HDS/HDN effectiveness factor. This study provides insights into the engineering of catalyst particle shapes and pore structures for improving HDS/HDN catalyst particle efficiency.

关键词： hydrodesulfurization     hydrodenitrogenation     particle shape     pore structure    

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Vibration analysis of blade-disc coupled structure of compressor

WANG Chunjie, SONG Shunguang, ZONG Xiao

《能源前沿（英文）》 2008年 第2卷 第3期   页码 302-305 doi: 10.1007/s11708-008-0064-8

摘要： While a 3D assembly model of blade-disc structure was established, a finite element model for calculating the vibration characteristics during blade-disc coupling was built by taking into consideration the coupling action of contact stress between the blade and the disc. The vibration characteristics of the blade-disc coupling structure was calculated and analyzed using cycle analysis method with the aid of ANSYS software. The modeling experiment shows that this method is feasible for analyzing the rabbet assembly structure.

关键词： blade-disc coupling     assembly     experiment     vibration     blade-disc structure    

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Construction of digital 3D magic-cube organization structure for innovation-driven manufacturing

《工程管理前沿（英文）》   页码 373-390 doi: 10.1007/s42524-022-0237-x

摘要： Owing to the heterogeneity between functional units and resource scarcity, manufacturing firms have been struggling with intra-organizational coordination for productivity and innovation. Traditional organizational structures, such as linear-functional and matrix, may cause responsibility division and independent goals (Shahani, 2020), and are more difficult to be adopted by large-sized innovative manufacturing firms for quantity production. This is based on a review of several new forms of organization (i.e., network organization, multiteam system, and platform organization) compared with the traditional forms of organization (i.e., linear, matrix, and business unit organization, among others). This study proposes a three-dimensional (3D) magic-cube organizational structure, considering the product dimensions, business, and administration. Moreover, the characteristics, propositions of system operation, system dynamic model, and working model of the 3D magic-cube organization are described. Finally, the 3D model is applied in a Chinese manufacturing firm to test its effectiveness. By redesigning the post and pay system, the pilot organization establishes a project-driven and cross-functional coordination mechanism, positively affecting the firm’s financial profit, output value, labor productivity, and income of per capita. The proposed 3D model can be adopted by large- or medium-sized manufacturing firms for product development and innovation. The implications of both practice and theory are also discussed in this study.

关键词： innovation     manufacturing     3D magic-cube organization structure     coordination    

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PID neural network control of a membrane structure inflation system

Qiushuang LIU, Xiaoli XU

《机械工程前沿（英文）》 2010年 第5卷 第4期   页码 418-422 doi: 10.1007/s11465-010-0117-7

摘要： Because it is difficult for the traditional PID algorithm for nonlinear time-variant control objects to obtain satisfactory control results, this paper studies a neuron PID controller. The neuron PID controller makes use of neuron self-learning ability, complies with certain optimum indicators, and automatically adjusts the parameters of the PID controller and makes them adapt to changes in the controlled object and the input reference signals. The PID controller is used to control a nonlinear time-variant membrane structure inflation system. Results show that the neural network PID controller can adapt to the changes in system structure parameters and fast track the changes in the input signal with high control precision.

关键词： PID     neural network     membrane structure    

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Modeling of specific structure crystallization coupling with dissolution

Yuanhui JI, Hongliang QIAN, Chang LIU, Xiaohua LU, Xin FENG, Xiaoyan JI,

《化学科学与工程前沿（英文）》 2010年 第4卷 第1期   页码 52-56 doi: 10.1007/s11705-009-0301-7

摘要： In this paper, the research framework for specific structure crystallization modeling has been proposed in which four steps are required in order to investigate the rigorous crystallization modeling by thermodynamics. The first is the activity coefficient model of the solution, the second is Solid-Liquid equilibrium, the third and fourth are the dissolution and crystallization kinetics modeling, respectively. Our investigations show that the mechanisms of complex structure formation and microphase transition can be analyzed by combining the dissolution and crystallization kinetics modeling. Moreover, the formation mechanism of the porous KCl has been analyzed, which may provide a reference for the porous structure formation in the advanced material synthesis.

关键词： structure crystallization     activity coefficient     reference     KCl     dissolution    

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标题 作者 时间 类型 操作

Mechanical design and analysis of a novel variable stiffness actuator with symmetrical pivot adjustment

期刊论文

Different manipulation mode analysis of a radial symmetrical hexapod robot with leg–arm integration

期刊论文

Fracture behavior of two non-symmetrical collinear cracks emanating from an elliptical hole in a piezoelectric

Junhong GUO, Zixing LU

期刊论文

电力系统中对称和/或不对称故障的限流器阻抗优化新方法

Mahmoud MODARESI, Hamid LESANI

期刊论文

Influence of pore structure on biologically activated carbon performance and biofilm microbial characteristics

期刊论文

Hierarchical fractal structure of perfect single-layer graphene

T. Zhang, K. Ding

期刊论文

Floating forest: A novel breakwater-windbreak structure against wind and wave hazards

期刊论文

Bicontinuous porous membranes with micro-nano composite structure using a facile atomization-assisted

期刊论文

Smart optical-fiber structure monitoring based on granular computing

Guan LU, Dakai LIANG,

期刊论文

Automated classification of civil structure defects based on convolutional neural network

Pierclaudio SAVINO, Francesco TONDOLO

期刊论文

Catalyst particle shapes and pore structure engineering for hydrodesulfurization and hydrodenitrogenation

期刊论文

Vibration analysis of blade-disc coupled structure of compressor

WANG Chunjie, SONG Shunguang, ZONG Xiao

期刊论文

Construction of digital 3D magic-cube organization structure for innovation-driven manufacturing

期刊论文

PID neural network control of a membrane structure inflation system

Qiushuang LIU, Xiaoli XU

期刊论文

Modeling of specific structure crystallization coupling with dissolution

Yuanhui JI, Hongliang QIAN, Chang LIU, Xiaohua LU, Xin FENG, Xiaoyan JI,

期刊论文